diff --git a/Project.toml b/Project.toml
index 2d76c69e..bea4bf08 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "FunSQL"
 uuid = "cf6cc811-59f4-4a10-b258-a8547a8f6407"
-authors = ["Kirill Simonov <xi@resolvent.net>", "Clark C. Evans <cce@clarkevans.com>"]
 version = "0.15.0"
+authors = ["Kirill Simonov <xi@resolvent.net>", "Clark C. Evans <cce@clarkevans.com>"]
 
 [deps]
 DBInterface = "a10d1c49-ce27-4219-8d33-6db1a4562965"
@@ -11,6 +11,7 @@ LRUCache = "8ac3fa9e-de4c-5943-b1dc-09c6b5f20637"
 OrderedCollections = "bac558e1-5e72-5ebc-8fee-abe8a469f55d"
 PrettyPrinting = "54e16d92-306c-5ea0-a30b-337be88ac337"
 Tables = "bd369af6-aec1-5ad0-b16a-f7cc5008161c"
+URIs = "5c2747f8-b7ea-4ff2-ba2e-563bfd36b1d4"
 
 [compat]
 DBInterface = "2.5"
@@ -19,4 +20,5 @@ LRUCache = "1.3"
 OrderedCollections = "1.4"
 PrettyPrinting = "0.3.2, 0.4"
 Tables = "1.6"
+URIs = "1.6.1"
 julia = "1.10"
diff --git a/src/FunSQL.jl b/src/FunSQL.jl
index fb6a5ca8..1f99cf5a 100644
--- a/src/FunSQL.jl
+++ b/src/FunSQL.jl
@@ -56,6 +56,7 @@ export
     funsql_group,
     funsql_highlight,
     funsql_in,
+    funsql_into,
     funsql_iterate,
     funsql_is_not_null,
     funsql_is_null,
@@ -94,6 +95,7 @@ using Tables
 using DBInterface
 using LRUCache
 using DataAPI
+using URIs
 
 const SQLLiteralType =
     Union{Missing, Bool, Number, AbstractString, Dates.AbstractTime}
diff --git a/src/catalogs.jl b/src/catalogs.jl
index 0fbd446a..1fe7f2e6 100644
--- a/src/catalogs.jl
+++ b/src/catalogs.jl
@@ -31,22 +31,24 @@ _metadata_get(dict::SQLMetadata, key::Union{Symbol, AbstractString}, default; st
     end
 
 """
-    SQLColumn(; name, metadata = nothing)
-    SQLColumn(name; metadata = nothing)
+    SQLColumn(; name, private = false, metadata = nothing)
+    SQLColumn(name; private = false, metadata = nothing)
 
 `SQLColumn` represents a column with the given `name` and optional `metadata`.
+If `private` is `true`, the column is excluded from the default query output.
 """
 struct SQLColumn
     name::Symbol
+    private::Bool
     metadata::SQLMetadata
 
-    function SQLColumn(; name::Union{Symbol, AbstractString}, metadata = nothing)
-        new(Symbol(name), _metadata(metadata))
+    function SQLColumn(; name::Union{Symbol, AbstractString}, private = false, metadata = nothing)
+        new(Symbol(name), private, _metadata(metadata))
     end
 end
 
-SQLColumn(name; metadata = nothing) =
-    SQLColumn(name = name, metadata = metadata)
+SQLColumn(name; private = false, metadata = nothing) =
+    SQLColumn(; name, private, metadata)
 
 Base.show(io::IO, col::SQLColumn) =
     print(io, quoteof(col, limit = true))
@@ -56,6 +58,9 @@ Base.show(io::IO, ::MIME"text/plain", col::SQLColumn) =
 
 function PrettyPrinting.quoteof(col::SQLColumn; limit::Bool = false)
     ex = Expr(:call, nameof(SQLColumn), QuoteNode(col.name))
+    if col.private
+        push(ex.args, Expr(:kw, :private, col.private))
+    end
     if !isempty(col.metadata)
         push!(ex.args, Expr(:kw, :metadata, limit ? :… : quoteof(reverse!(collect(col.metadata)))))
     end
@@ -122,10 +127,10 @@ struct SQLTable <: AbstractDict{Symbol, SQLColumn}
 end
 
 SQLTable(name; qualifiers = Symbol[], columns, metadata = nothing) =
-    SQLTable(qualifiers = qualifiers, name = name, columns = columns, metadata = metadata)
+    SQLTable(; qualifiers, name, columns, metadata)
 
 SQLTable(name, columns...; qualifiers = Symbol[], metadata = nothing) =
-    SQLTable(qualifiers = qualifiers, name = name, columns = [columns...], metadata = metadata)
+    SQLTable(; qualifiers, name, columns = [columns...], metadata)
 
 _column_map(columns::OrderedDict{Symbol, SQLColumn}) =
     columns
@@ -280,7 +285,7 @@ struct SQLCatalog <: AbstractDict{Symbol, SQLTable}
 end
 
 SQLCatalog(tables...; dialect = :default, cache = default_cache_maxsize, metadata = nothing) =
-    SQLCatalog(tables = tables, dialect = dialect, cache = cache, metadata = metadata)
+    SQLCatalog(; tables, dialect, cache, metadata)
 
 _table_map(tables::Dict{Symbol, SQLTable}) =
     tables
diff --git a/src/clauses/internal.jl b/src/clauses/internal.jl
index 8eea0184..6f069dbe 100644
--- a/src/clauses/internal.jl
+++ b/src/clauses/internal.jl
@@ -4,10 +4,10 @@
 
 struct WithContextClause <: AbstractSQLClause
     dialect::SQLDialect
-    columns::Union{Vector{SQLColumn}, Nothing}
+    table::Union{SQLTable, Nothing}
 
-    WithContextClause(; dialect, columns = nothing) =
-        new(dialect, columns)
+    WithContextClause(; dialect, table = nothing) =
+        new(dialect, table)
 end
 
 const WITH_CONTEXT = SQLSyntaxCtor{WithContextClause}(:WITH_CONTEXT)
@@ -17,8 +17,8 @@ function PrettyPrinting.quoteof(c::WithContextClause, ctx::QuoteContext)
     if c.dialect !== default_dialect
         push!(ex.args, Expr(:kw, :dialect, quoteof(c.dialect)))
     end
-    if c.columns !== nothing
-        push!(ex.args, Expr(:kw, :columns, Expr(:vect, Any[quoteof(col) for col in c.columns]...)))
+    if c.table !== nothing
+        push!(ex.args, Expr(:kw, :table, quoteof(c.table)))
     end
     ex
 end
diff --git a/src/link.jl b/src/link.jl
index 00015f41..85aed317 100644
--- a/src/link.jl
+++ b/src/link.jl
@@ -25,18 +25,44 @@ struct LinkContext
             knot_refs)
 end
 
+function _select(t::RowType)
+    args = Pair{SQLColumn, SQLQuery}[]
+    for (f, ft) in t.fields
+        !(f in t.private_fields) || continue
+        lbl = escapefield(f)
+        if ft isa ScalarType
+            push!(args, SQLColumn(lbl) => Get(f))
+        else
+            nested_args = _select(ft)
+            for (nested_col, nested_ref) in nested_args
+                nested_lbl = Symbol(lbl, '.', nested_col.name)
+                nested_col = SQLColumn(nested_lbl)
+                push!(args, nested_col => Nested(name = f, tail = nested_ref))
+            end
+        end
+    end
+    args
+end
+
+escapefield(f::Symbol) =
+    Symbol(escapefield(string(f)))
+
+escapefield(f) =
+    escapeuri(f, c -> c == ' ' || c != '.' && URIs.issafe(c))
+
 function link(q::SQLQuery)
     @dissect(q, (local tail) |> WithContext(catalog = (local catalog))) || throw(IllFormedError())
     ctx = LinkContext(catalog)
     t = row_type(tail)
-    refs = SQLQuery[]
-    for (f, ft) in t.fields
-        if ft isa ScalarType
-            push!(refs, Get(f))
-        end
+    col_refs = _select(t)
+    columns = first.(col_refs)
+    if isempty(columns)
+        columns = [SQLColumn(:_)]
     end
+    table = SQLTable(escapefield(label(q)), columns = columns)
+    refs = last.(col_refs)
     tail′ = Linked(refs, tail = link(dismantle(tail, ctx), ctx, refs))
-    WithContext(tail = tail′, catalog = catalog, defs = ctx.defs)
+    WithContext(tail = tail′, catalog = catalog, table = table, defs = ctx.defs)
 end
 
 function dismantle(q::SQLQuery, ctx)
@@ -123,19 +149,15 @@ function dismantle(n::GroupNode, ctx)
     Group(by = by′, sets = n.sets, name = n.name, label_map = n.label_map, tail = tail′)
 end
 
-function dismantle(n::IterateNode, ctx)
+function dismantle(n::IntoNode, ctx)
     tail′ = dismantle(ctx)
-    iterator′ = dismantle(n.iterator, ctx)
-    Iterate(iterator = iterator′, tail = tail′)
+    Into(name = n.name, tail = tail′)
 end
 
-function dismantle(n::JoinNode, ctx)
-    rt = row_type(n.joinee)
-    router = JoinRouter(Set(keys(rt.fields)), !isa(rt.group, EmptyType))
+function dismantle(n::IterateNode, ctx)
     tail′ = dismantle(ctx)
-    joinee′ = dismantle(n.joinee, ctx)
-    on′ = dismantle_scalar(n.on, ctx)
-    RoutedJoin(joinee = joinee′, on = on′, router = router, left = n.left, right = n.right, optional = n.optional, tail = tail′)
+    iterator′ = dismantle(n.iterator, ctx)
+    Iterate(iterator = iterator′, tail = tail′)
 end
 
 function dismantle(n::LimitNode, ctx)
@@ -181,6 +203,13 @@ function dismantle_scalar(n::ResolvedNode, ctx)
     end
 end
 
+function dismantle(n::RoutedJoinNode, ctx)
+    tail′ = dismantle(ctx)
+    joinee′ = dismantle(n.joinee, ctx)
+    on′ = dismantle_scalar(n.on, ctx)
+    RoutedJoin(joinee = joinee′, on = on′, name = n.name, left = n.left, right = n.right, optional = n.optional, tail = tail′)
+end
+
 function dismantle(n::SelectNode, ctx)
     tail′ = dismantle(ctx)
     args′ = dismantle_scalar(n.args, ctx)
@@ -232,16 +261,7 @@ function link(n::AppendNode, ctx)
 end
 
 function link(n::AsNode, ctx)
-    refs = SQLQuery[]
-    for ref in ctx.refs
-        if @dissect(ref, (local tail) |> Nested(name = (local name)))
-            @assert name == n.name
-            push!(refs, tail)
-        else
-            error()
-        end
-    end
-    tail′ = link(ctx.tail, ctx, refs)
+    tail′ = link(ctx)
     As(name = n.name, tail = tail′)
 end
 
@@ -289,17 +309,28 @@ function link(n::FromIterateNode, ctx)
 end
 
 function link(n::FromTableExpressionNode, ctx)
-    refs = ctx.cte_refs[(n.name, n.depth)]
-    for ref in ctx.refs
-        push!(refs, Nested(name = n.name, tail = ref))
-    end
+    cte_refs = ctx.cte_refs[(n.name, n.depth)]
+    append!(cte_refs, ctx.refs)
     n
 end
 
 function link(n::GroupNode, ctx)
-    has_aggregates = any(ref -> @dissect(ref, Agg() || Agg() |> Nested()), ctx.refs)
-    if !has_aggregates && isempty(n.by)
-        return link(FromNothing(), ctx)
+    krefs = SQLQuery[]
+    arefs = SQLQuery[]
+    has_aggregates = false
+    for ref in ctx.refs
+        if @dissect(ref, (local tail) |> Nested(name = (local name))) && name === n.name
+            gather!(tail, ctx, arefs)
+            has_aggregates = true
+        elseif @dissect(ref, Agg()) && n.name === nothing
+            push!(arefs, ref)
+            has_aggregates = true
+        else
+            push!(krefs, ref)
+        end
+    end
+    if isempty(arefs) && isempty(n.by)
+        return link(n.name !== nothing ? Into(n.name, tail = FromNothing()) : FromNothing(), ctx)
     end
     # Some group keys are added both to SELECT and to GROUP BY.
     # To avoid duplicate SQL, they must be evaluated in a nested subquery.
@@ -312,16 +343,16 @@ function link(n::GroupNode, ctx)
     # Ignore `SELECT DISTINCT` case.
     if has_aggregates
         ctx′ = LinkContext(ctx, refs = refs)
-        for ref in ctx.refs
-            if (@dissect(ref, nothing |> Agg(args = (local args), filter = (local filter)) |> Nested(name = (local name))) && name === n.name) ||
-               (@dissect(ref, nothing |> Agg(args = (local args), filter = (local filter))) && n.name === nothing)
-                gather!(args, ctx′)
-                if filter !== nothing
-                    gather!(filter, ctx′)
-                end
-            elseif @dissect(ref, nothing |> Get(name = (local name))) && name in keys(n.label_map)
-                # Force evaluation in a nested subquery.
-                push!(refs, n.by[n.label_map[name]])
+        for ref in krefs
+            @dissect(ref, Get(name = (local name))) && name in keys(n.label_map) || error()
+            # Force evaluation in a nested subquery.
+            push!(refs, n.by[n.label_map[name]])
+        end
+        for ref in arefs
+            @dissect(ref, Agg(args = (local args), filter = (local filter))) || error()
+            gather!(args, ctx′)
+            if filter !== nothing
+                gather!(filter, ctx′)
             end
         end
     end
@@ -333,6 +364,20 @@ function link(n::GroupNode, ctx)
     Group(by = n.by, sets = n.sets, name = n.name, label_map = n.label_map, tail = tail′)
 end
 
+function link(n::IntoNode, ctx)
+    refs = SQLQuery[]
+    for ref in ctx.refs
+        if @dissect(ref, (local tail) |> Nested(name = (local name)))
+            @assert name == n.name
+            gather!(tail, ctx, refs)
+        else
+            error()
+        end
+    end
+    tail′ = Linked(refs, 0, tail = link(ctx.tail, ctx, refs))
+    Into(name = n.name, tail = tail′)
+end
+
 function link(n::IterateNode, ctx)
     iterator′ = n.iterator
     defs = copy(ctx.defs)
@@ -364,53 +409,6 @@ function link(n::IterateNode, ctx)
     Padding(tail = q′)
 end
 
-function route(r::JoinRouter, ref::SQLQuery)
-    if @dissect(ref, Nested(name = (local name))) && name in r.label_set
-        return 1
-    end
-    if @dissect(ref, Get(name = (local name))) && name in r.label_set
-        return 1
-    end
-    if @dissect(ref, Agg()) && r.group
-        return 1
-    end
-    return -1
-end
-
-function link(n::RoutedJoinNode, ctx)
-    lrefs = SQLQuery[]
-    rrefs = SQLQuery[]
-    for ref in ctx.refs
-        turn = route(n.router, ref)
-        push!(turn < 0 ? lrefs : rrefs, ref)
-    end
-    if n.optional && isempty(rrefs)
-        return link(ctx)
-    end
-    ln_ext_refs = length(lrefs)
-    rn_ext_refs = length(rrefs)
-    refs′ = SQLQuery[]
-    lateral_refs = SQLQuery[]
-    gather!(n.joinee, ctx, lateral_refs)
-    append!(lrefs, lateral_refs)
-    lateral = !isempty(lateral_refs)
-    gather!(n.on, ctx, refs′)
-    for ref in refs′
-        turn = route(n.router, ref)
-        push!(turn < 0 ? lrefs : rrefs, ref)
-    end
-    tail′ = Linked(lrefs, ln_ext_refs, tail = link(ctx.tail, ctx, lrefs))
-    joinee′ = Linked(rrefs, rn_ext_refs, tail = link(n.joinee, ctx, rrefs))
-    RoutedJoin(
-        joinee = joinee′,
-        on = n.on,
-        router = n.router,
-        left = n.left,
-        right = n.right,
-        lateral = lateral,
-        tail = tail′)
-end
-
 function link(n::LimitNode, ctx)
     tail′ = Linked(ctx.refs, tail = link(ctx))
     Limit(offset = n.offset, limit = n.limit, tail = tail′)
@@ -433,16 +431,14 @@ end
 
 function link(n::PartitionNode, ctx)
     refs = SQLQuery[]
-    imm_refs = SQLQuery[]
-    ctx′ = LinkContext(ctx, refs = imm_refs)
+    arefs = SQLQuery[]
     has_aggregates = false
     for ref in ctx.refs
-        if (@dissect(ref, nothing |> Agg(args = (local args), filter = (local filter)) |> Nested(name = (local name))) && name === n.name) ||
-            (@dissect(ref, nothing |> Agg(args = (local args), filter = (local filter))) && n.name === nothing)
-            gather!(args, ctx′)
-            if filter !== nothing
-                gather!(filter, ctx′)
-            end
+        if @dissect(ref, (local tail) |> Nested(name = (local name))) && name === n.name
+            gather!(tail, ctx, arefs)
+            has_aggregates = true
+        elseif @dissect(ref, Agg()) && n.name === nothing
+            push!(arefs, ref)
             has_aggregates = true
         else
             push!(refs, ref)
@@ -451,6 +447,15 @@ function link(n::PartitionNode, ctx)
     if !has_aggregates
         return link(ctx)
     end
+    imm_refs = SQLQuery[]
+    ctx′ = LinkContext(ctx, refs = imm_refs)
+    for ref in arefs
+        @dissect(ref, Agg(args = (local args), filter = (local filter))) || error()
+        gather!(args, ctx′)
+        if filter !== nothing
+            gather!(filter, ctx′)
+        end
+    end
     gather!(n.by, ctx′)
     gather!(n.order_by, ctx′)
     n_ext_refs = length(refs)
@@ -459,6 +464,46 @@ function link(n::PartitionNode, ctx)
     Partition(by = n.by, order_by = n.order_by, frame = n.frame, name = n.name, tail = tail′)
 end
 
+function link(n::RoutedJoinNode, ctx)
+    lrefs = SQLQuery[]
+    rrefs = SQLQuery[]
+    for ref in ctx.refs
+        if @dissect(ref, Nested(name = (local name))) && name === n.name
+            push!(rrefs, ref)
+        else
+            push!(lrefs, ref)
+        end
+    end
+    if n.optional && isempty(rrefs)
+        return link(ctx)
+    end
+    ln_ext_refs = length(lrefs)
+    rn_ext_refs = length(rrefs)
+    refs′ = SQLQuery[]
+    lateral_refs = SQLQuery[]
+    gather!(n.joinee, ctx, lateral_refs)
+    append!(lrefs, lateral_refs)
+    lateral = !isempty(lateral_refs)
+    gather!(n.on, ctx, refs′)
+    for ref in refs′
+        if @dissect(ref, Nested(name = (local name))) && name === n.name
+            push!(rrefs, ref)
+        else
+            push!(lrefs, ref)
+        end
+    end
+    tail′ = Linked(lrefs, ln_ext_refs, tail = link(ctx.tail, ctx, lrefs))
+    joinee′ = Linked(rrefs, rn_ext_refs, tail = link(Into(name = n.name, tail = n.joinee), ctx, rrefs))
+    RoutedJoin(
+        joinee = joinee′,
+        on = n.on,
+        name = n.name,
+        left = n.left,
+        right = n.right,
+        lateral = lateral,
+        tail = tail′)
+end
+
 function link(n::SelectNode, ctx)
     refs = SQLQuery[]
     gather!(n.args, ctx, refs)
@@ -556,12 +601,9 @@ end
 function gather!(n::IsolatedNode, ctx)
     def = ctx.defs[n.idx]
     !@dissect(def, Linked()) || return
-    refs = SQLQuery[]
-    for (f, ft) in n.type.fields
-        if ft isa ScalarType
-            push!(refs, Get(f))
-            break
-        end
+    refs = last.(_select(n.type))
+    if !isempty(refs)
+        refs = refs[1:1]
     end
     def′ = Linked(refs, tail = link(def, ctx, refs))
     ctx.defs[n.idx] = def′
diff --git a/src/nodes.jl b/src/nodes.jl
index ab470726..b8e68a13 100644
--- a/src/nodes.jl
+++ b/src/nodes.jl
@@ -54,17 +54,19 @@ terminal(q::SQLQuery) =
 Chain(q′, q) =
     convert(SQLQuery, q)(q′)
 
-label(q::SQLQuery) =
-    @something label(q.head) label(q.tail)
+function label(q::SQLQuery; default = :_)
+    l = label(q.head)
+    l !== nothing ? l : label(q.tail; default)
+end
 
 label(n::AbstractSQLNode) =
     nothing
 
-label(::Nothing) =
-    :_
+label(::Nothing; default = :_) =
+    default
 
-label(q) =
-    label(convert(SQLQuery, q))
+label(q; default = :_) =
+    label(convert(SQLQuery, q); default)
 
 
 # A variant of SQLQuery for assembling a chain of identifiers.
@@ -913,6 +915,7 @@ include("nodes/get.jl")
 include("nodes/group.jl")
 include("nodes/highlight.jl")
 include("nodes/internal.jl")
+include("nodes/into.jl")
 include("nodes/iterate.jl")
 include("nodes/join.jl")
 include("nodes/limit.jl")
diff --git a/src/nodes/as.jl b/src/nodes/as.jl
index 3a4a5db7..d1a61a2d 100644
--- a/src/nodes/as.jl
+++ b/src/nodes/as.jl
@@ -16,8 +16,7 @@ AsNode(name) =
     As(name; tail = nothing)
     name => tail
 
-In a scalar context, `As` specifies the name of the output column.  When
-applied to tabular data, `As` wraps the data in a nested record.
+`As` specifies the name of the output column.
 
 The arrow operator (`=>`) is a shorthand notation for `As`.
 
@@ -35,19 +34,19 @@ SELECT "person_1"."person_id" AS "id"
 FROM "person" AS "person_1"
 ```
 
-*Show all patients together with their state of residence.*
+*Show all patients together with their primary care provider.*
 
 ```jldoctest
-julia> person = SQLTable(:person, columns = [:person_id, :year_of_birth, :location_id]);
+julia> person = SQLTable(:person, columns = [:person_id, :year_of_birth, :provider_id]);
 
-julia> location = SQLTable(:location, columns = [:location_id, :state]);
+julia> provider = SQLTable(:provider, columns = [:provider_id, :provider_name]);
 
 julia> q = From(:person) |>
-           Join(From(:location) |> As(:location),
-                on = Get.location_id .== Get.location.location_id) |>
-           Select(Get.person_id, Get.location.state);
+           Join(From(:provider) |> As(:pcp),
+                on = Get.provider_id .== Get.pcp.provider_id) |>
+           Select(Get.person_id, Get.pcp.provider_name);
 
-julia> print(render(q, tables = [person, location]))
+julia> print(render(q, tables = [person, provider]))
 SELECT
   "person_1"."person_id",
   "location_1"."state"
diff --git a/src/nodes/define.jl b/src/nodes/define.jl
index fab058de..3fd44dfc 100644
--- a/src/nodes/define.jl
+++ b/src/nodes/define.jl
@@ -4,13 +4,14 @@ struct DefineNode <: TabularNode
     args::Vector{SQLQuery}
     before::Union{Symbol, Bool}
     after::Union{Symbol, Bool}
+    private::Bool
     label_map::OrderedDict{Symbol, Int}
 
-    function DefineNode(; args = [], before = nothing, after = nothing, label_map = nothing)
+    function DefineNode(; args = [], before = nothing, after = nothing, private = false, label_map = nothing)
         if label_map !== nothing
-            n = new(args, something(before, false), something(after, false), label_map)
+            n = new(args, something(before, false), something(after, false), private, label_map)
         else
-            n = new(args, something(before, false), something(after, false), OrderedDict{Symbol, Int}())
+            n = new(args, something(before, false), something(after, false), private, OrderedDict{Symbol, Int}())
             populate_label_map!(n)
         end
         if (n.before isa Symbol || n.before) && (n.after isa Symbol || n.after)
@@ -20,12 +21,12 @@ struct DefineNode <: TabularNode
     end
 end
 
-DefineNode(args...; before = nothing, after = nothing) =
-    DefineNode(args = SQLQuery[args...], before = before, after = after)
+DefineNode(args...; before = nothing, after = nothing, private = false) =
+    DefineNode(args = SQLQuery[args...], before = before, after = after, private = private)
 
 """
-    Define(; args = [], before = nothing, after = nothing, tail = nothing)
-    Define(args...; before = nothing, after = nothing, tail = nothing)
+    Define(; args = [], before = nothing, after = nothing, private = false, tail = nothing)
+    Define(args...; before = nothing, after = nothing, private = false, tail = nothing)
 
 The `Define` node adds or replaces output columns.
 
@@ -35,6 +36,8 @@ both new and replaced columns at the end (after a specified column).
 Alternatively, set `before = true` (`before = <column>`) to add both new and
 replaced columns at the front (before the specified column).
 
+If `private` is set, the columns will be excluded from the query output.
+
 # Examples
 
 *Show patients who are at least 16 years old.*
@@ -90,5 +93,8 @@ function PrettyPrinting.quoteof(n::DefineNode, ctx::QuoteContext)
     if n.after !== false
         push!(ex.args, Expr(:kw, :after, n.after isa Symbol ? QuoteNode(n.after) : n.after))
     end
+    if n.private !== false
+        push!(ex.args, Expr(:kw, :private, n.private))
+    end
     ex
 end
diff --git a/src/nodes/function.jl b/src/nodes/function.jl
index aae32314..cc60dbf4 100644
--- a/src/nodes/function.jl
+++ b/src/nodes/function.jl
@@ -160,9 +160,6 @@ const funsql_fun = Fun
 transliterate(::typeof(Fun), name::Symbol, ctx::TransliterateContext, @nospecialize(args...)) =
     Fun(name, args = [transliterate(SQLQuery, arg, ctx) for arg in args])
 
-terminal(::Type{FunctionNode}) =
-    true
-
 PrettyPrinting.quoteof(n::FunctionNode, ctx::QuoteContext) =
     Expr(:call,
          Expr(:., :Fun,
diff --git a/src/nodes/internal.jl b/src/nodes/internal.jl
index 91f866fd..5ec0bd44 100644
--- a/src/nodes/internal.jl
+++ b/src/nodes/internal.jl
@@ -4,9 +4,10 @@
 struct WithContextNode <: AbstractSQLNode
     catalog::SQLCatalog
     defs::Vector{SQLQuery}
+    table::Union{SQLTable, Nothing}
 
-    WithContextNode(; catalog = SQLCatalog(), defs = SQLQuery[]) =
-        new(catalog, defs)
+    WithContextNode(; catalog = SQLCatalog(), defs = SQLQuery[], table = nothing) =
+        new(catalog, defs, table)
 end
 
 const WithContext = SQLQueryCtor{WithContextNode}(:WithContext)
@@ -17,6 +18,9 @@ function PrettyPrinting.quoteof(n::WithContextNode, ctx::QuoteContext)
     if !isempty(n.defs)
         push!(ex.args, Expr(:kw, :defs, Expr(:vect, Any[quoteof(def, ctx) for def in n.defs]...)))
     end
+    if n.table !== nothing
+        push!(ex.args, Expr(:kw, :table, quoteof(n.table)))
+    end
     ex
 end
 
@@ -203,29 +207,21 @@ PrettyPrinting.quoteof(n::FromFunctionNode, ctx::QuoteContext) =
 
 
 # Annotated Join node.
-struct JoinRouter
-    label_set::Set{Symbol}
-    group::Bool
-end
-
-PrettyPrinting.quoteof(r::JoinRouter) =
-    Expr(:call, :JoinRouter, quoteof(r.label_set), quoteof(r.group))
-
 struct RoutedJoinNode <: TabularNode
     joinee::SQLQuery
     on::SQLQuery
-    router::JoinRouter
+    name::Symbol
     left::Bool
     right::Bool
     lateral::Bool
     optional::Bool
 
-    RoutedJoinNode(; joinee, on, router, left, right, lateral = false, optional = false) =
-        new(joinee, on, router, left, right, lateral, optional)
+    RoutedJoinNode(; joinee, on, name = label(joinee), left, right, lateral = false, optional = false) =
+        new(joinee, on, name, left, right, lateral, optional)
 end
 
-RoutedJoinNode(joinee, on; router, left = false, right = false, lateral = false, optional = false) =
-    RoutedJoinNode(joinee = joinee, on = on, router, left = left, right = right, lateral = lateral, optional = optional)
+RoutedJoinNode(joinee, on; name = label(joinee), left = false, right = false, lateral = false, optional = false) =
+    RoutedJoinNode(name = name, on = on, router, left = left, right = right, lateral = lateral, optional = optional)
 
 const RoutedJoin = SQLQueryCtor{RoutedJoinNode}(:RoutedJoin)
 
@@ -234,7 +230,7 @@ function PrettyPrinting.quoteof(n::RoutedJoinNode, ctx::QuoteContext)
     if !ctx.limit
         push!(ex.args, quoteof(n.joinee, ctx))
         push!(ex.args, quoteof(n.on, ctx))
-        push!(ex.args, Expr(:kw, :router, quoteof(n.router)))
+        push!(ex.args, Expr(:kw, :name, QuoteNode(n.name)))
         if n.left
             push!(ex.args, Expr(:kw, :left, n.left))
         end
@@ -310,7 +306,7 @@ PrettyPrinting.quoteof(n::FunSQLMacroNode, ctx::QuoteContext) =
     Expr(:macrocall, Symbol("@funsql"), n.line, !ctx.limit ? n.ex : :…)
 
 label(n::FunSQLMacroNode) =
-    label(n.query)
+    label(n.query, default = nothing)
 
 
 # Unwrap @funsql macro when displaying the query.
diff --git a/src/nodes/into.jl b/src/nodes/into.jl
new file mode 100644
index 00000000..655652c0
--- /dev/null
+++ b/src/nodes/into.jl
@@ -0,0 +1,33 @@
+# Wrap the output into a nested record.
+
+mutable struct IntoNode <: TabularNode
+    name::Symbol
+    private::Bool
+
+    IntoNode(; name::Union{Symbol, AbstractString}, private::Bool = false) =
+        new(Symbol(name), private)
+end
+
+IntoNode(name; private = false) =
+    IntoNode(; name, private)
+
+"""
+    Into(; name, private = false, tail = nothing)
+    Into(name; private = false, tail = nothing)
+
+`Into` wraps output columns in a nested record.
+"""
+const Into = SQLQueryCtor{IntoNode}(:Into)
+
+const funsql_into = Into
+
+function PrettyPrinting.quoteof(n::IntoNode, ctx::QuoteContext)
+    ex = Expr(:call, :Into, quoteof(n.name))
+    if n.private
+        push!(ex.args, Expr(:kw, :private, n.private))
+    end
+    ex
+end
+
+label(n::IntoNode) =
+    n.name
diff --git a/src/nodes/join.jl b/src/nodes/join.jl
index c1bc2eb4..027914f3 100644
--- a/src/nodes/join.jl
+++ b/src/nodes/join.jl
@@ -6,21 +6,23 @@ mutable struct JoinNode <: TabularNode
     left::Bool
     right::Bool
     optional::Bool
+    swap::Bool
+    private::Bool
 
-    JoinNode(; joinee, on, left = false, right = false, optional = false) =
-        new(joinee, on, left, right, optional)
+    JoinNode(; joinee, on, left = false, right = false, optional = false, swap = false, private = false) =
+        new(joinee, on, left, right, optional, swap, private)
 end
 
-JoinNode(joinee; on, left = false, right = false, optional = false) =
-    JoinNode(; joinee, on, left, right, optional)
+JoinNode(joinee; on, left = false, right = false, optional = false, swap = false, private = false) =
+    JoinNode(; joinee, on, left, right, optional, swap, private)
 
-JoinNode(joinee, on; left = false, right = false, optional = false) =
-    JoinNode(; joinee, on, left, right, optional)
+JoinNode(joinee, on; left = false, right = false, optional = false, swap = false, private = false) =
+    JoinNode(; joinee, on, left, right, optional, swap, private)
 
 """
-    Join(; joinee, on, left = false, right = false, optional = false)
-    Join(joinee; on, left = false, right = false, optional = false)
-    Join(joinee, on; left = false, right = false, optional = false)
+    Join(; joinee, on, left = false, right = false, optional = false, swap = false, private = false)
+    Join(joinee; on, left = false, right = false, optional = false, swap = false, private = false)
+    Join(joinee, on; left = false, right = false, optional = false, swap = false, private = false)
 
 `Join` correlates two input datasets.
 
@@ -102,8 +104,17 @@ function PrettyPrinting.quoteof(n::JoinNode, ctx::QuoteContext)
         if n.optional
             push!(ex.args, Expr(:kw, :optional, n.optional))
         end
+        if n.swap
+            push!(ex.args, Expr(:kw, :swap, n.swap))
+        end
+        if n.private
+            push!(ex.args, Expr(:kw, :private, n.private))
+        end
     else
         push!(ex.args, :…)
     end
     ex
 end
+
+label(n::JoinNode) =
+    n.swap ? label(n.joinee) : nothing
diff --git a/src/nodes/literal.jl b/src/nodes/literal.jl
index f4ff534e..593be93d 100644
--- a/src/nodes/literal.jl
+++ b/src/nodes/literal.jl
@@ -45,8 +45,5 @@ Base.convert(::Type{SQLQuery}, val::SQLLiteralType) =
 Base.convert(::Type{SQLQuery}, ref::Base.RefValue) =
     Lit(ref.x)
 
-terminal(::Type{LiteralNode}) =
-    true
-
 PrettyPrinting.quoteof(n::LiteralNode, ctx::QuoteContext) =
     Expr(:call, :Lit, n.val)
diff --git a/src/resolve.jl b/src/resolve.jl
index 73bf67ac..5608f7c1 100644
--- a/src/resolve.jl
+++ b/src/resolve.jl
@@ -178,9 +178,8 @@ end
 
 function resolve(n::AsNode, ctx)
     tail′ = resolve(ctx)
-    t = row_type(tail′)
     q′ = As(name = n.name, tail = tail′)
-    Resolved(RowType(FieldTypeMap(n.name => t)), tail = q′)
+    Resolved(type(tail′), tail = q′)
 end
 
 function resolve_scalar(n::AsNode, ctx)
@@ -264,16 +263,28 @@ function resolve(n::DefineNode, ctx)
             end
         end
     end
+    private_fields = copy(t.private_fields)
+    for l in keys(n.label_map)
+        if n.private
+            push!(private_fields, l)
+        else
+            delete!(private_fields, l)
+        end
+    end
     q′ = Define(args = args′, label_map = n.label_map, tail = tail′)
-    Resolved(RowType(fields, t.group), tail = q′)
+    Resolved(RowType(fields, t.group, private_fields), tail = q′)
 end
 
 function RowType(table::SQLTable)
     fields = FieldTypeMap()
-    for f in keys(table.columns)
+    private_fields = Set{Symbol}()
+    for (f, c) in table.columns
         fields[f] = ScalarType()
+        if c.private
+            push!(private_fields, f)
+        end
     end
-    RowType(fields)
+    RowType(fields, EmptyType(), private_fields)
 end
 
 function resolve(n::FromNode, ctx)
@@ -331,6 +342,10 @@ function resolve(n::FromNode, ctx)
 end
 
 function resolve_scalar(n::FunctionNode, ctx)
+    if ctx.tail !== nothing
+        q′ = unnest(ctx.tail, convert(SQLQuery, n), ctx)
+        return resolve_scalar(q′, ctx)
+    end
     args′ = resolve_scalar(n.args, ctx)
     q′ = Fun(name = n.name, args = args′)
     Resolved(ScalarType(), tail = q′)
@@ -356,7 +371,7 @@ resolve_scalar(n::FunSQLMacroNode, ctx) =
 
 function resolve(n::GetNode, ctx)
     if ctx.tail !== nothing
-        q′ = unnest(ctx.tail, Get(n.name), ctx)
+        q′ = unnest(ctx.tail, convert(SQLQuery, n), ctx)
         return resolve(q′, ctx)
     end
     resolve(FromNode(n.name), ctx)
@@ -364,7 +379,7 @@ end
 
 function resolve_scalar(n::GetNode, ctx)
     if ctx.tail !== nothing
-        q′ = unnest(ctx.tail, Get(n.name), ctx)
+        q′ = unnest(ctx.tail, convert(SQLQuery, n), ctx)
         return resolve_scalar(q′, ctx)
     end
     t = get(ctx.row_type.fields, n.name, EmptyType())
@@ -391,8 +406,12 @@ function resolve(n::GroupNode, ctx)
         fields[n.name] = RowType(FieldTypeMap(), group)
         group = EmptyType()
     end
-    q′ = Group(by = by′, sets = n.sets, label_map = n.label_map, tail = tail′)
-    Resolved(RowType(fields, group), tail = q′)
+    private_fields = Set{Symbol}()
+    if n.name !== nothing
+        push!(private_fields, n.name)
+    end
+    q′ = Group(by = by′, sets = n.sets, name = n.name, label_map = n.label_map, tail = tail′)
+    Resolved(RowType(fields, group, private_fields), tail = q′)
 end
 
 resolve(::HighlightNode, ctx) =
@@ -401,6 +420,14 @@ resolve(::HighlightNode, ctx) =
 resolve_scalar(::HighlightNode, ctx) =
     resolve_scalar(ctx)
 
+function resolve(n::IntoNode, ctx)
+    tail′ = resolve(ctx)
+    t = row_type(tail′)
+    q′ = Into(name = n.name, tail = tail′)
+    t′ = RowType(FieldTypeMap(n.name => t), EmptyType(), n.private ? Set([n.name]) : Set{Symbol}())
+    Resolved(t′, tail = q′)
+end
+
 function resolve(n::IterateNode, ctx)
     tail′ = resolve(ResolveContext(ctx, knot_type = nothing, implicit_knot = false))
     t = row_type(tail′)
@@ -416,23 +443,30 @@ function resolve(n::IterateNode, ctx)
 end
 
 function resolve(n::JoinNode, ctx)
+    if n.swap
+        ctx′ = ResolveContext(ctx, tail = n.joinee)
+        return resolve(JoinNode(joinee = ctx.tail, on = n.on, left = n.right, right = n.left, optional = n.optional, private = n.private), ctx′)
+    end
     tail′ = resolve(ctx)
     lt = row_type(tail′)
+    name = label(n.joinee)
     joinee′ = resolve(n.joinee, ResolveContext(ctx, row_type = lt, implicit_knot = false))
     rt = row_type(joinee′)
     fields = FieldTypeMap()
     for (f, ft) in lt.fields
-        fields[f] = get(rt.fields, f, ft)
+        fields[f] = ft
     end
-    for (f, ft) in rt.fields
-        if !haskey(fields, f)
-            fields[f] = ft
-        end
+    fields[name] = rt
+    group = lt.group
+    private_fields = copy(lt.private_fields)
+    if n.private
+        push!(private_fields, name)
+    else
+        delete!(private_fields, name)
     end
-    group = rt.group isa EmptyType ? lt.group : rt.group
-    t = RowType(fields, group)
+    t = RowType(fields, group, private_fields)
     on′ = resolve_scalar(n.on, ctx, t)
-    q′ = Join(joinee = joinee′, on = on′, left = n.left, right = n.right, optional = n.optional, tail = tail′)
+    q′ = RoutedJoin(joinee = joinee′, on = on′, name = name, left = n.left, right = n.right, optional = n.optional, tail = tail′)
     Resolved(t, tail = q′)
 end
 
@@ -447,6 +481,10 @@ function resolve(n::LimitNode, ctx)
 end
 
 function resolve_scalar(n::LiteralNode, ctx)
+    if ctx.tail !== nothing
+        q′ = unnest(ctx.tail, convert(SQLQuery, n), ctx)
+        return resolve_scalar(q′, ctx)
+    end
     Resolved(ScalarType(), tail = convert(SQLQuery, n))
 end
 
@@ -483,8 +521,12 @@ function resolve(n::PartitionNode, ctx)
         end
         fields[n.name] = RowType(FieldTypeMap(), t)
     end
+    private_fields = copy(t.private_fields)
+    if n.name !== nothing
+        push!(private_fields, n.name)
+    end
     q′ = Partition(by = by′, order_by = order_by′, frame = n.frame, name = n.name, tail = tail′)
-    Resolved(RowType(fields, group), tail = q′)
+    Resolved(RowType(fields, group, private_fields), tail = q′)
 end
 
 function resolve(n::SelectNode, ctx)
@@ -532,16 +574,7 @@ function resolve(n::Union{WithNode, WithExternalNode}, ctx)
         v = get(ctx.cte_types, name, nothing)
         depth = 1 + (v !== nothing ? v[1] : 0)
         t = row_type(args′[i])
-        cte_t = get(t.fields, name, EmptyType())
-        if !(cte_t isa RowType)
-            throw(
-                ReferenceError(
-                    REFERENCE_ERROR_TYPE.INVALID_TABLE_REFERENCE,
-                    name = name,
-                    path = get_path(ctx)))
-
-        end
-        cte_types′ = Base.ImmutableDict(cte_types′, name => (depth, cte_t))
+        cte_types′ = Base.ImmutableDict(cte_types′, name => (depth, t))
     end
     ctx′ = ResolveContext(ctx, cte_types = cte_types′)
     tail′ = resolve(ctx′)
diff --git a/src/serialize.jl b/src/serialize.jl
index 16d8a8b5..02deb302 100644
--- a/src/serialize.jl
+++ b/src/serialize.jl
@@ -13,11 +13,11 @@ mutable struct SerializeContext <: IO
 end
 
 function serialize(s::SQLSyntax)
-    @dissect(s, WITH_CONTEXT(tail = (local s′), dialect = (local dialect), columns = (local columns))) || throw(IllFormedError())
+    @dissect(s, WITH_CONTEXT(tail = (local s′), dialect = (local dialect), table = (local table))) || throw(IllFormedError())
     ctx = SerializeContext(dialect, s′)
     serialize!(ctx)
     raw = String(take!(ctx.io))
-    SQLString(raw, columns = columns, vars = ctx.vars)
+    SQLString(raw, table = table, vars = ctx.vars)
 end
 
 Base.write(ctx::SerializeContext, octet::UInt8) =
diff --git a/src/strings.jl b/src/strings.jl
index 122a8848..c0d2cce6 100644
--- a/src/strings.jl
+++ b/src/strings.jl
@@ -5,7 +5,8 @@
 
 Serialized SQL query.
 
-Parameter `columns` is a vector describing the output columns.
+Parameter `table` is an optional `SQLTable` object describing the output of
+the query.
 
 Parameter `vars` is a vector of query parameters (created with [`Var`](@ref))
 in the order they are expected by the `DBInterface.execute()` function.
@@ -55,11 +56,11 @@ SQLString(\"""
 """
 struct SQLString <: AbstractString
     raw::String
-    columns::Union{Vector{SQLColumn}, Nothing}
+    table::Union{SQLTable, Nothing}
     vars::Vector{Symbol}
 
-    SQLString(raw; columns = nothing, vars = Symbol[]) =
-        new(raw, columns, vars)
+    SQLString(raw; table = nothing, vars = Symbol[]) =
+        new(raw, table, vars)
 end
 
 Base.ncodeunits(sql::SQLString) =
@@ -88,8 +89,8 @@ Base.write(io::IO, sql::SQLString) =
 
 function PrettyPrinting.quoteof(sql::SQLString)
     ex = Expr(:call, nameof(SQLString), sql.raw)
-    if sql.columns !== nothing
-        push!(ex.args, Expr(:kw, :columns, Expr(:vect, Any[quoteof(col) for col in sql.columns]...)))
+    if sql.table !== nothing
+        push!(ex.args, Expr(:kw, :table, quoteof(sql.table)))
     end
     if !isempty(sql.vars)
         push!(ex.args, Expr(:kw, :vars, quoteof(sql.vars)))
@@ -100,10 +101,11 @@ end
 function Base.show(io::IO, sql::SQLString)
     print(io, "SQLString(")
     show(io, sql.raw)
-    if sql.columns !== nothing
-        print(io, ", columns = ")
-        l = length(sql.columns)
-        print(io, l == 0 ? "[]" : l == 1 ? "[…1 column…]" : "[…$l columns…]")
+    if sql.table !== nothing
+        print(io, ", table = SQLTable(")
+        show(io, sql.table.name)
+        l = length(sql.table.columns)
+        print(io, ", ", l == 0 ? "[]" : l == 1 ? "[…1 column…]" : "[…$l columns…]", ")")
     end
     if !isempty(sql.vars)
         print(io, ", vars = ")
diff --git a/src/translate.jl b/src/translate.jl
index 84b3bd79..a616b1ef 100644
--- a/src/translate.jl
+++ b/src/translate.jl
@@ -39,10 +39,13 @@ function complete(a::Assemblage)
 end
 
 # Add a SELECT clause aligned with the exported references.
-function complete_aligned(a::Assemblage, ctx)
+function complete_aligned(a::Assemblage, ctx, expected_names = nothing)
+    names = collect(keys(a.cols))
+    expected_names = something(expected_names, names)
     aligned =
         length(a.cols) == length(ctx.refs) &&
-        all(a.repl[ref] === name for (name, ref) in zip(keys(a.cols), ctx.refs))
+        all(a.repl[ref] === name for (name, ref) in zip(names, ctx.refs)) &&
+        names == expected_names
     !aligned || return complete(a)
     if !@dissect(a.syntax, SELECT() || UNION())
         alias = nothing
@@ -54,9 +57,9 @@ function complete_aligned(a::Assemblage, ctx)
     subs = make_subs(a, alias)
     repl = Dict{SQLQuery, Symbol}()
     cols = OrderedDict{Symbol, SQLSyntax}()
-    for ref in ctx.refs
-        name = repl[ref] = a.repl[ref]
-        cols[name] = subs[ref]
+    for (expected_name, ref) in zip(expected_names, ctx.refs)
+        cols[expected_name] = subs[ref]
+        repl[ref] = expected_name
     end
     a′ = Assemblage(a.name, syntax, repl = repl, cols = cols)
     complete(a′)
@@ -172,6 +175,7 @@ struct TranslateContext
     refs::Vector{SQLQuery}
     vars::Base.ImmutableDict{Tuple{Symbol, Int}, SQLSyntax}
     subs::Dict{SQLQuery, SQLSyntax}
+    partition::Union{SQLSyntax, Nothing}
 
     TranslateContext(; catalog, defs) =
         new(catalog,
@@ -184,9 +188,10 @@ struct TranslateContext
             0,
             SQLQuery[],
             Base.ImmutableDict{Tuple{Symbol, Int}, SQLSyntax}(),
-            Dict{Int, SQLSyntax}())
+            Dict{Int, SQLSyntax}(),
+            nothing)
 
-    function TranslateContext(ctx::TranslateContext; tail = ctx.tail, cte_map = ctx.cte_map, knot = ctx.knot, refs = ctx.refs, vars = ctx.vars, subs = ctx.subs)
+    function TranslateContext(ctx::TranslateContext; tail = ctx.tail, cte_map = ctx.cte_map, knot = ctx.knot, refs = ctx.refs, vars = ctx.vars, subs = ctx.subs, partition = ctx.partition)
         new(ctx.catalog,
             tail,
             ctx.defs,
@@ -197,7 +202,8 @@ struct TranslateContext
             knot,
             refs,
             vars,
-            subs)
+            subs,
+            partition)
     end
 end
 
@@ -211,15 +217,11 @@ function allocate_alias(ctx::TranslateContext, alias::Symbol)
 end
 
 function translate(q::SQLQuery)
-    @dissect(q, (local q′) |> Linked(refs = (local refs)) |> WithContext(catalog = (local catalog), defs = (local defs))) || throw(IllFormedError())
+    @dissect(q, (local q′) |> Linked(refs = (local refs)) |> WithContext(catalog = (local catalog), table = (local table), defs = (local defs))) || throw(IllFormedError())
     ctx = TranslateContext(catalog = catalog, defs = defs)
     ctx′ = TranslateContext(ctx, refs = refs)
     base = assemble(q′, ctx′)
-    columns = nothing
-    if !isempty(refs)
-        columns = [SQLColumn(base.repl[ref]) for ref in refs]
-    end
-    c = complete_aligned(base, ctx′)
+    c = complete_aligned(base, ctx′, collect(keys(table)))
     with_args = SQLSyntax[]
     for cte_a in ctx.ctes
         !cte_a.external || continue
@@ -238,7 +240,7 @@ function translate(q::SQLQuery)
     if !isempty(with_args)
         c = WITH(tail = c, args = with_args, recursive = ctx.recursive[])
     end
-    WITH_CONTEXT(tail = c, dialect = ctx.catalog.dialect, columns = columns)
+    WITH_CONTEXT(tail = c, dialect = ctx.catalog.dialect, table = table)
 end
 
 function translate(q::SQLQuery, ctx)
@@ -266,9 +268,10 @@ function translate(q, ctx::TranslateContext, subs::Dict{SQLQuery, SQLSyntax})
 end
 
 function translate(n::AggregateNode, ctx)
-    args = translate(n.args, ctx)
-    filter = translate(n.filter, ctx)
-    AGG(n.name, args = args, filter = filter)
+    ctx′ = ctx.partition !== nothing ? TranslateContext(ctx, partition = nothing) : ctx
+    args = translate(n.args, ctx′)
+    filter = translate(n.filter, ctx′)
+    AGG(n.name, args = args, filter = filter, over = ctx.partition)
 end
 
 function translate(n::AsNode, ctx)
@@ -427,26 +430,8 @@ function assemble(n::AppendNode, ctx)
     Assemblage(a_name, s, repl = repl, cols = dummy_cols)
 end
 
-function assemble(n::AsNode, ctx)
-    refs′ = SQLQuery[]
-    for ref in ctx.refs
-        if @dissect(ref, (local tail) |> Nested())
-            push!(refs′, tail)
-        else
-            push!(refs′, ref)
-        end
-    end
-    base = assemble(TranslateContext(ctx, refs = refs′))
-    repl′ = Dict{SQLQuery, Symbol}()
-    for ref in ctx.refs
-        if @dissect(ref, (local tail) |> Nested())
-            repl′[ref] = base.repl[tail]
-        else
-            repl′[ref] = base.repl[ref]
-        end
-    end
-    Assemblage(n.name, base.syntax, cols = base.cols, repl = repl′)
-end
+assemble(n::AsNode, ctx) =
+    assemble(ctx)
 
 function assemble(n::BindNode, ctx)
     vars′ = ctx.vars
@@ -472,7 +457,6 @@ function assemble(n::DefineNode, ctx)
     for (f, i) in n.label_map
         tr_cache[f] = translate(n.args[i], ctx, subs)
     end
-    repl = Dict{SQLQuery, Symbol}()
     trns = Pair{SQLQuery, SQLSyntax}[]
     for ref in ctx.refs
         if @dissect(ref, nothing |> Get(name = (local name))) && name in keys(tr_cache)
@@ -530,21 +514,12 @@ end
 assemble(::FromNothingNode, ctx) =
     assemble(nothing, ctx)
 
-function unwrap_repl(a::Assemblage)
-    repl′ = Dict{SQLQuery, Symbol}()
-    for (ref, name) in a.repl
-        @dissect(ref, (local tail) |> Nested()) || error()
-        repl′[tail] = name
-    end
-    Assemblage(a.name, a.syntax, cols = a.cols, repl = repl′)
-end
-
 function assemble(n::FromTableExpressionNode, ctx)
     cte_a = ctx.ctes[ctx.cte_map[(n.name, n.depth)]]
     alias = allocate_alias(ctx, n.name)
     tbl = convert(SQLSyntax, (cte_a.qualifiers, cte_a.name))
     s = FROM(AS(name = alias, tail = tbl))
-    subs = make_subs(unwrap_repl(cte_a.a), alias)
+    subs = make_subs(cte_a.a, alias)
     trns = Pair{SQLQuery, SQLSyntax}[]
     for ref in ctx.refs
         push!(trns, ref => subs[ref])
@@ -634,7 +609,9 @@ function assemble(n::FromValuesNode, ctx)
 end
 
 function assemble(n::GroupNode, ctx)
-    has_aggregates = any(ref -> @dissect(ref, Agg() || Agg() |> Nested()), ctx.refs)
+    has_aggregates =
+        n.name === nothing && any(ref -> @dissect(ref, Agg()), ctx.refs) ||
+        any(ref -> @dissect(ref, Nested(name = (local name))) && name == n.name, ctx.refs)
     if isempty(n.by) && !has_aggregates # NOOP: already processed in link()
         return assemble(nothing, ctx)
     end
@@ -652,9 +629,9 @@ function assemble(n::GroupNode, ctx)
         if @dissect(ref, nothing |> Get(name = (local name)))
             @assert name in keys(n.label_map)
             push!(trns, ref => by[n.label_map[name]])
-        elseif @dissect(ref, nothing |> Agg())
+        elseif n.name === nothing && @dissect(ref, nothing |> Agg())
             push!(trns, ref => translate(ref, ctx, subs))
-        elseif @dissect(ref, (local tail = nothing |> Agg()) |> Nested())
+        elseif @dissect(ref, (local tail) |> Nested(name = (local name))) && name == n.name
             push!(trns, ref => translate(tail, ctx, subs))
         end
     end
@@ -675,6 +652,33 @@ function assemble(n::GroupNode, ctx)
     return Assemblage(base.name, s, cols = cols, repl = repl)
 end
 
+function assemble(n::IntoNode, ctx)
+    base = assemble(ctx)
+    if all(@dissect(ref, (local tail) |> Nested()) && tail in keys(base.repl) for ref in ctx.refs)
+        repl′ = Dict{SQLQuery, Symbol}()
+        for ref in ctx.refs
+            @dissect(ref, (local tail) |> Nested()) || error()
+            repl′[ref] = base.repl[tail]
+        end
+        return Assemblage(n.name, base.syntax, cols = base.cols, repl = repl′)
+    end
+    if !@dissect(base.syntax, SELECT() || UNION())
+        base_alias = nothing
+        s = base.syntax
+    else
+        base_alias = allocate_alias(ctx, base)
+        s = FROM(AS(name = base_alias, tail = complete(base)))
+    end
+    subs = make_subs(base, base_alias)
+    trns = Pair{SQLQuery, SQLSyntax}[]
+    for ref in ctx.refs
+        @dissect(ref, (local tail) |> Nested()) || error()
+        push!(trns, ref => translate(tail, ctx, subs))
+    end
+    repl, cols = make_repl_cols(trns)
+    Assemblage(base.name, s, cols = cols, repl = repl)
+end
+
 function assemble(n::IterateNode, ctx)
     ctx′ = TranslateContext(ctx, vars = Base.ImmutableDict{Tuple{Symbol, Int}, SQLSyntax}())
     left = assemble(ctx)
@@ -846,14 +850,13 @@ function assemble(n::PartitionNode, ctx)
     partition = PARTITION(by = by, order_by = order_by, frame = n.frame)
     trns = Pair{SQLQuery, SQLSyntax}[]
     has_aggregates = false
+    ctx′′ = TranslateContext(ctx′, partition = partition)
     for ref in ctx.refs
         if @dissect(ref, nothing |> Agg()) && n.name === nothing
-            @dissect(translate(ref, ctx′), AGG(name = (local name), args = (local args), filter = (local filter))) || error()
-            push!(trns, ref => AGG(; name, args, filter, over = partition))
+            push!(trns, ref => translate(ref, ctx′′))
             has_aggregates = true
-        elseif @dissect(ref, (local tail = nothing |> Agg()) |> Nested(name = (local name))) && name === n.name
-            @dissect(translate(tail, ctx′), AGG(name = (local name), args = (local args), filter = (local filter))) || error()
-            push!(trns, ref => AGG(; name, args, filter, over = partition))
+        elseif @dissect(ref, (local tail) |> Nested(name = (local name))) && name === n.name
+            push!(trns, ref => translate(tail, ctx′′))
             has_aggregates = true
         else
             push!(trns, ref => subs[ref])
@@ -883,22 +886,16 @@ function assemble(n::RoutedJoinNode, ctx)
         right = assemble(n.joinee, ctx)
     end
     if @dissect(right.syntax, (local joinee = (ID() || AS())) |> FROM()) && (!n.left || _outer_safe(right))
-        for (ref, name) in right.repl
-            subs[ref] = right.cols[name]
-        end
+        right_alias = nothing
         if ctx.catalog.dialect.has_implicit_lateral
             lateral = false
         end
     else
         right_alias = allocate_alias(ctx, right)
         joinee = AS(name = right_alias, tail = complete(right))
-        right_cache = Dict{Symbol, SQLSyntax}()
-        for (ref, name) in right.repl
-            subs[ref] = get(right_cache, name) do
-                ID(name = name, tail = right_alias)
-            end
-        end
     end
+    right_subs = make_subs(right, right_alias)
+    merge!(subs, right_subs)
     on = translate(n.on, ctx, subs)
     s = JOIN(joinee = joinee, on = on, left = n.left, right = n.right, lateral = lateral, tail = tail)
     trns = Pair{SQLQuery, SQLSyntax}[]
diff --git a/src/types.jl b/src/types.jl
index 856821ed..24d0c369 100644
--- a/src/types.jl
+++ b/src/types.jl
@@ -13,17 +13,21 @@ PrettyPrinting.quoteof(::EmptyType) =
     Expr(:call, nameof(EmptyType))
 
 struct ScalarType <: AbstractSQLType
+    ScalarType() =
+        new()
 end
 
-PrettyPrinting.quoteof(::ScalarType) =
+function PrettyPrinting.quoteof(t::ScalarType)
     Expr(:call, nameof(ScalarType))
+end
 
 struct RowType <: AbstractSQLType
     fields::OrderedDict{Symbol, Union{ScalarType, RowType}}
     group::Union{EmptyType, RowType}
+    private_fields::Set{Symbol}
 
-    RowType(fields, group = EmptyType()) =
-        new(fields, group)
+    RowType(fields, group = EmptyType(), private_fields = Set{Symbol}()) =
+        new(fields, group, private_fields)
 end
 
 const FieldTypeMap = OrderedDict{Symbol, Union{ScalarType, RowType}}
@@ -32,8 +36,8 @@ const GroupType = Union{EmptyType, RowType}
 RowType() =
     RowType(FieldTypeMap())
 
-RowType(fields::Pair{Symbol, <:AbstractSQLType}...; group = EmptyType()) =
-    RowType(FieldTypeMap(fields), group)
+RowType(fields::Pair{Symbol, <:AbstractSQLType}...; group = EmptyType(), private_fields = Set{Symbol}()) =
+    RowType(FieldTypeMap(fields), group, private_fields)
 
 function PrettyPrinting.quoteof(t::RowType)
     ex = Expr(:call, nameof(RowType))
@@ -43,6 +47,9 @@ function PrettyPrinting.quoteof(t::RowType)
     if !(t.group isa EmptyType)
         push!(ex.args, Expr(:kw, :group, quoteof(t.group)))
     end
+    if !isempty(t.private_fields)
+        push!(ex.args, Expr(:kw, :private_fields, t.private_fields))
+    end
     ex
 end
 
@@ -62,16 +69,20 @@ function Base.intersect(t1::RowType, t2::RowType)
         return t1
     end
     fields = FieldTypeMap()
+    private_fields = Set{Symbol}()
     for f in keys(t1.fields)
         if f in keys(t2.fields)
             t = intersect(t1.fields[f], t2.fields[f])
             if !isa(t, EmptyType)
                 fields[f] = t
+                if f in t1.private_fields && f in t2.private_fields
+                    push!(private_fields, f)
+                end
             end
         end
     end
     group = intersect(t1.group, t2.group)
-    RowType(fields, group)
+    RowType(fields, group, private_fields)
 end
 
 
@@ -91,7 +102,7 @@ function Base.issubset(t1::RowType, t2::RowType)
         return true
     end
     for f in keys(t1.fields)
-        if !(f in keys(t2.fields) && issubset(t1.fields[f], t2.fields[f]))
+        if !(f in keys(t2.fields) && issubset(t1.fields[f], t2.fields[f]) && (!(f in t1.private_fields) || f in t2.private_fields))
             return false
         end
     end