fix(editor): keep nested indentation for set operations in subqueries and CTEs (#1698)

CHANGELOG.md

@@ -24,6 +24,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - A dropped Redis connection now reconnects on the next command and replays auth and the selected database, instead of failing until the next health check. (#1701)
 - DuckDB VARIANT columns now show their value as text instead of an empty cell.
 - A new database group now appears in the connection list right away instead of only after restarting the app. (#1704)
+- The SQL formatter keeps nested indentation for UNION, UNION ALL, INTERSECT, and EXCEPT inside a derived table or CTE, and puts the closing parenthesis of a subquery on its own line instead of collapsing it onto the last SELECT. (#1698)
 
 ## [0.51.1] - 2026-06-16
 

TablePro/Core/Services/Formatting/SQLFormatterService.swift

@@ -105,7 +105,6 @@ internal struct SQLTokenFormatter {
 
     // Mutable state
     private var output = ""
-    private var indent = 0
     private var clauseStack: [ClauseContext] = []
     private var afterNewline = true
     private var isFirstClause = true
@@ -210,8 +209,8 @@ internal struct SQLTokenFormatter {
             output += String(repeating: "\n", count: newlineCount)
             afterNewline = true
             isFirstClause = true
-            indent = 0
             clauseStack.removeAll()
+            selectColumnIndentStack.removeAll()
             inSelectColumns = false
 
         case ",":
@@ -256,7 +255,6 @@ internal struct SQLTokenFormatter {
             }
             output += "\n"
             selectColumnIndentStack.append(selectColumnIndent)
-            indent += 1
             afterNewline = true
             isFirstClause = true
             suppressNextSpace = false
@@ -268,7 +266,6 @@ internal struct SQLTokenFormatter {
             output += " ("
             output += "\n"
             selectColumnIndentStack.append(selectColumnIndent)
-            indent += 1
             afterNewline = true
             isFirstClause = true
             suppressNextSpace = false
@@ -279,7 +276,6 @@ internal struct SQLTokenFormatter {
         if clauseStack.contains(.createTable) && !clauseStack.contains(.createTableBody) {
             output += " ("
             output += "\n"
-            indent += 1
             afterNewline = true
             suppressNextSpace = false
             clauseStack.append(.createTableBody)
@@ -318,9 +314,8 @@ internal struct SQLTokenFormatter {
             return
         }
         // Block paren (subquery or CREATE TABLE body): pop back to the block opener
-        if let idx = clauseStack.lastIndex(where: { $0 == .subquery || $0 == .createTableBody }) {
+        if let idx = clauseStack.lastIndex(where: Self.isBlockContext) {
             clauseStack.removeSubrange(idx...)
-            indent = max(0, indent - 1)
             output += "\n" + indentStr() + ")"
             afterNewline = false
             isFirstClause = false
@@ -375,7 +370,7 @@ internal struct SQLTokenFormatter {
             appendToken(kw)
         case "HAVING", "LIMIT", "OFFSET":
             handleClauseKeyword(kw: kw, context: nil)
-        case "UNION", "INTERSECT", "EXCEPT":
+        case "UNION", "INTERSECT", "EXCEPT", "MINUS":
             handleSetOperation(upper: upper, kw: kw, next: next)
         case "ALL":
             // standalone ALL (not consumed by UNION ALL)
@@ -528,14 +523,23 @@ internal struct SQLTokenFormatter {
 
     private mutating func handleSetOperation(upper: String, kw: String, next: SQLToken?) {
         inSelectColumns = false
-        indent = 0
-        clauseStack.removeAll()
+        if let blockIdx = clauseStack.lastIndex(where: Self.isBlockContext) {
+            clauseStack.removeSubrange((blockIdx + 1)...)
+        } else {
+            clauseStack.removeAll()
+        }
+
+        var line = kw
         if upper == "UNION" && next?.upperValue == "ALL" {
             let allKw = options.uppercaseKeywords ? "ALL" : "all"
-            output += "\n\n" + kw + " " + allKw + "\n\n"
+            line += " " + allKw
             skipCount = 1 // skip ALL
+        }
+
+        if clauseStack.contains(where: Self.isBlockContext) {
+            output += "\n" + indentStr() + line + "\n"
         } else {
-            output += "\n\n" + kw + "\n\n"
+            output += "\n\n" + line + "\n\n"
         }
         afterNewline = true
         isFirstClause = true
@@ -600,6 +604,16 @@ internal struct SQLTokenFormatter {
 
     private var currentContext: ClauseContext? { clauseStack.last }
 
+    private static func isBlockContext(_ ctx: ClauseContext) -> Bool {
+        ctx == .subquery || ctx == .createTableBody
+    }
+
+    private var indent: Int {
+        clauseStack.reduce(into: 0) { depth, ctx in
+            if Self.isBlockContext(ctx) { depth += 1 }
+        }
+    }
+
     private mutating func replaceTop(with ctx: ClauseContext) {
         if !clauseStack.isEmpty { clauseStack.removeLast() }
         clauseStack.append(ctx)

TableProTests/Core/Services/SQLFormatterServiceTests.swift

@@ -438,4 +438,196 @@ struct SQLFormatterServiceTests {
         FROM employees
         """)
     }
+
+    @Test("Window frame ROWS BETWEEN stays inline")
+    func windowFrameInline() throws {
+        let result = try format("select sum(x) over (order by id rows between unbounded preceding and current row) as running from t")
+        let lines = result.split(separator: "\n", omittingEmptySubsequences: false)
+        #expect(lines.count == 2)
+        #expect(lines[0].contains("ROWS BETWEEN"))
+        #expect(lines[1] == "FROM t")
+    }
+
+    // MARK: - Set Operations Inside Subqueries and CTEs
+
+    @Test("UNION inside a derived table keeps nesting and closes on its own line")
+    func unionInDerivedTable() throws {
+        let sql = "select country, avg(score) as score "
+            + "from (select yr, country, score from scores "
+            + "union select 2024, country, ladder from scores_current) as final "
+            + "group by country"
+        let result = try format(sql)
+        #expect(result == """
+        SELECT country,
+               avg(score) AS score
+        FROM (
+          SELECT yr,
+                 country,
+                 score
+          FROM scores
+          UNION
+          SELECT 2024,
+                 country,
+                 ladder
+          FROM scores_current
+        ) AS final
+        GROUP BY country
+        """)
+    }
+
+    @Test("UNION ALL inside a derived table")
+    func unionAllInDerivedTable() throws {
+        let result = try format("select * from (select id from a union all select id from b) as t")
+        #expect(result == """
+        SELECT *
+        FROM (
+          SELECT id
+          FROM a
+          UNION ALL
+          SELECT id
+          FROM b
+        ) AS t
+        """)
+    }
+
+    @Test("INTERSECT inside a derived table")
+    func intersectInDerivedTable() throws {
+        let result = try format("select * from (select id from a intersect select id from b) as t")
+        #expect(result == """
+        SELECT *
+        FROM (
+          SELECT id
+          FROM a
+          INTERSECT
+          SELECT id
+          FROM b
+        ) AS t
+        """)
+    }
+
+    @Test("EXCEPT inside a derived table")
+    func exceptInDerivedTable() throws {
+        let result = try format("select * from (select id from a except select id from b) as t")
+        #expect(result == """
+        SELECT *
+        FROM (
+          SELECT id
+          FROM a
+          EXCEPT
+          SELECT id
+          FROM b
+        ) AS t
+        """)
+    }
+
+    @Test("MINUS inside a derived table (Oracle)")
+    func minusInDerivedTable() throws {
+        let result = try formatter.format(
+            "select * from (select id from a minus select id from b) as t",
+            dialect: .oracle
+        ).formattedSQL
+        #expect(result == """
+        SELECT *
+        FROM (
+          SELECT id
+          FROM a
+          MINUS
+          SELECT id
+          FROM b
+        ) AS t
+        """)
+    }
+
+    @Test("UNION inside a CTE body")
+    func unionInsideCTE() throws {
+        let result = try format("with combined as (select id from a union select id from b) select * from combined")
+        #expect(result == """
+        WITH combined AS (
+          SELECT id
+          FROM a
+          UNION
+          SELECT id
+          FROM b
+        )
+        SELECT *
+        FROM combined
+        """)
+    }
+
+    @Test("UNION inside a nested subquery keeps both levels")
+    func unionInNestedSubquery() throws {
+        let result = try format("select * from (select id from (select id from t union select id from u) as iq) as oq")
+        #expect(result == """
+        SELECT *
+        FROM (
+          SELECT id
+          FROM (
+            SELECT id
+            FROM t
+            UNION
+            SELECT id
+            FROM u
+          ) AS iq
+        ) AS oq
+        """)
+    }
+
+    @Test("Chained top-level UNIONs keep blank-line separation")
+    func chainedTopLevelUnions() throws {
+        let result = try format("select 1 union select 2 union select 3")
+        #expect(result == """
+        SELECT 1
+
+        UNION
+
+        SELECT 2
+
+        UNION
+
+        SELECT 3
+        """)
+    }
+
+    @Test("Top-level INTERSECT keeps blank-line separation")
+    func topLevelIntersect() throws {
+        let result = try format("select id from a intersect select id from b")
+        #expect(result == """
+        SELECT id
+        FROM a
+
+        INTERSECT
+
+        SELECT id
+        FROM b
+        """)
+    }
+
+    @Test("INSERT ... SELECT")
+    func insertSelect() throws {
+        let result = try format("insert into t (a, b) select a, b from s")
+        #expect(result == """
+        INSERT INTO t (a, b)
+        SELECT a,
+               b
+        FROM s
+        """)
+    }
+
+    // MARK: - Idempotency of Nested Set Operations
+
+    @Test("UNION in derived table is idempotent")
+    func unionInDerivedTableIdempotent() throws {
+        let sql = "select * from (select id from a union select id from b) as t"
+        let first = try format(sql)
+        let second = try format(first)
+        #expect(first == second)
+    }
+
+    @Test("Nested subquery with UNION is idempotent")
+    func nestedUnionIdempotent() throws {
+        let sql = "select * from (select id from (select id from t union select id from u) as iq) as oq where id > 0"
+        let first = try format(sql)
+        let second = try format(first)
+        #expect(first == second)
+    }
 }