diff --git a/internal/endtoend/testdata/select_union/mysql/go/query.sql.go b/internal/endtoend/testdata/select_union/mysql/go/query.sql.go
index 011ef8eb07..ee09e09532 100644
--- a/internal/endtoend/testdata/select_union/mysql/go/query.sql.go
+++ b/internal/endtoend/testdata/select_union/mysql/go/query.sql.go
@@ -96,6 +96,35 @@ func (q *Queries) SelectUnion(ctx context.Context) ([]Foo, error) {
 	return items, nil
 }
 
+const selectUnionAliased = `-- name: SelectUnionAliased :many
+(SELECT a, b FROM foo)
+UNION
+SELECT a, b FROM bar
+`
+
+func (q *Queries) SelectUnionAliased(ctx context.Context) ([]Foo, error) {
+	rows, err := q.db.QueryContext(ctx, selectUnionAliased)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var items []Foo
+	for rows.Next() {
+		var i Foo
+		if err := rows.Scan(&i.A, &i.B); err != nil {
+			return nil, err
+		}
+		items = append(items, i)
+	}
+	if err := rows.Close(); err != nil {
+		return nil, err
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	return items, nil
+}
+
 const selectUnionOther = `-- name: SelectUnionOther :many
 SELECT a, b FROM foo
 UNION
diff --git a/internal/endtoend/testdata/select_union/mysql/query.sql b/internal/endtoend/testdata/select_union/mysql/query.sql
index d607aa7222..c706921bc3 100644
--- a/internal/endtoend/testdata/select_union/mysql/query.sql
+++ b/internal/endtoend/testdata/select_union/mysql/query.sql
@@ -22,4 +22,9 @@ SELECT * FROM foo;
 -- name: SelectUnionOther :many
 SELECT * FROM foo
 UNION
-SELECT * FROM bar;
\ No newline at end of file
+SELECT * FROM bar;
+
+-- name: SelectUnionAliased :many
+(SELECT * FROM foo)
+UNION
+SELECT * FROM bar;
diff --git a/internal/endtoend/testdata/select_union/postgres/pgx/v4/go/query.sql.go b/internal/endtoend/testdata/select_union/postgres/pgx/v4/go/query.sql.go
index 9380106f0c..0dc42e4d5b 100644
--- a/internal/endtoend/testdata/select_union/postgres/pgx/v4/go/query.sql.go
+++ b/internal/endtoend/testdata/select_union/postgres/pgx/v4/go/query.sql.go
@@ -87,6 +87,32 @@ func (q *Queries) SelectUnion(ctx context.Context) ([]Foo, error) {
 	return items, nil
 }
 
+const selectUnionAliased = `-- name: SelectUnionAliased :many
+(SELECT a, b FROM foo)
+UNION
+SELECT a, b FROM foo
+`
+
+func (q *Queries) SelectUnionAliased(ctx context.Context) ([]Foo, error) {
+	rows, err := q.db.Query(ctx, selectUnionAliased)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var items []Foo
+	for rows.Next() {
+		var i Foo
+		if err := rows.Scan(&i.A, &i.B); err != nil {
+			return nil, err
+		}
+		items = append(items, i)
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	return items, nil
+}
+
 const selectUnionOther = `-- name: SelectUnionOther :many
 SELECT a, b FROM foo
 UNION
diff --git a/internal/endtoend/testdata/select_union/postgres/pgx/v4/query.sql b/internal/endtoend/testdata/select_union/postgres/pgx/v4/query.sql
index 107aee02d2..f44f1fd2af 100644
--- a/internal/endtoend/testdata/select_union/postgres/pgx/v4/query.sql
+++ b/internal/endtoend/testdata/select_union/postgres/pgx/v4/query.sql
@@ -22,4 +22,9 @@ SELECT * FROM foo;
 -- name: SelectUnionOther :many
 SELECT * FROM foo
 UNION
-SELECT * FROM bar;
\ No newline at end of file
+SELECT * FROM bar;
+
+-- name: SelectUnionAliased :many
+(SELECT * FROM foo)
+UNION
+SELECT * FROM foo;
diff --git a/internal/endtoend/testdata/select_union/postgres/pgx/v5/go/query.sql.go b/internal/endtoend/testdata/select_union/postgres/pgx/v5/go/query.sql.go
index 9380106f0c..0dc42e4d5b 100644
--- a/internal/endtoend/testdata/select_union/postgres/pgx/v5/go/query.sql.go
+++ b/internal/endtoend/testdata/select_union/postgres/pgx/v5/go/query.sql.go
@@ -87,6 +87,32 @@ func (q *Queries) SelectUnion(ctx context.Context) ([]Foo, error) {
 	return items, nil
 }
 
+const selectUnionAliased = `-- name: SelectUnionAliased :many
+(SELECT a, b FROM foo)
+UNION
+SELECT a, b FROM foo
+`
+
+func (q *Queries) SelectUnionAliased(ctx context.Context) ([]Foo, error) {
+	rows, err := q.db.Query(ctx, selectUnionAliased)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var items []Foo
+	for rows.Next() {
+		var i Foo
+		if err := rows.Scan(&i.A, &i.B); err != nil {
+			return nil, err
+		}
+		items = append(items, i)
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	return items, nil
+}
+
 const selectUnionOther = `-- name: SelectUnionOther :many
 SELECT a, b FROM foo
 UNION
diff --git a/internal/endtoend/testdata/select_union/postgres/pgx/v5/query.sql b/internal/endtoend/testdata/select_union/postgres/pgx/v5/query.sql
index 107aee02d2..f44f1fd2af 100644
--- a/internal/endtoend/testdata/select_union/postgres/pgx/v5/query.sql
+++ b/internal/endtoend/testdata/select_union/postgres/pgx/v5/query.sql
@@ -22,4 +22,9 @@ SELECT * FROM foo;
 -- name: SelectUnionOther :many
 SELECT * FROM foo
 UNION
-SELECT * FROM bar;
\ No newline at end of file
+SELECT * FROM bar;
+
+-- name: SelectUnionAliased :many
+(SELECT * FROM foo)
+UNION
+SELECT * FROM foo;
diff --git a/internal/endtoend/testdata/select_union/postgres/stdlib/go/query.sql.go b/internal/endtoend/testdata/select_union/postgres/stdlib/go/query.sql.go
index ebc0fbb363..7579360f97 100644
--- a/internal/endtoend/testdata/select_union/postgres/stdlib/go/query.sql.go
+++ b/internal/endtoend/testdata/select_union/postgres/stdlib/go/query.sql.go
@@ -96,6 +96,35 @@ func (q *Queries) SelectUnion(ctx context.Context) ([]Foo, error) {
 	return items, nil
 }
 
+const selectUnionAliased = `-- name: SelectUnionAliased :many
+(SELECT a, b FROM foo)
+UNION
+SELECT a, b FROM foo
+`
+
+func (q *Queries) SelectUnionAliased(ctx context.Context) ([]Foo, error) {
+	rows, err := q.db.QueryContext(ctx, selectUnionAliased)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+	var items []Foo
+	for rows.Next() {
+		var i Foo
+		if err := rows.Scan(&i.A, &i.B); err != nil {
+			return nil, err
+		}
+		items = append(items, i)
+	}
+	if err := rows.Close(); err != nil {
+		return nil, err
+	}
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+	return items, nil
+}
+
 const selectUnionOther = `-- name: SelectUnionOther :many
 SELECT a, b FROM foo
 UNION
diff --git a/internal/endtoend/testdata/select_union/postgres/stdlib/query.sql b/internal/endtoend/testdata/select_union/postgres/stdlib/query.sql
index 107aee02d2..f44f1fd2af 100644
--- a/internal/endtoend/testdata/select_union/postgres/stdlib/query.sql
+++ b/internal/endtoend/testdata/select_union/postgres/stdlib/query.sql
@@ -22,4 +22,9 @@ SELECT * FROM foo;
 -- name: SelectUnionOther :many
 SELECT * FROM foo
 UNION
-SELECT * FROM bar;
\ No newline at end of file
+SELECT * FROM bar;
+
+-- name: SelectUnionAliased :many
+(SELECT * FROM foo)
+UNION
+SELECT * FROM foo;
diff --git a/internal/endtoend/testdata/select_union/sqlite/query.sql b/internal/endtoend/testdata/select_union/sqlite/query.sql
index d607aa7222..67d28d1824 100644
--- a/internal/endtoend/testdata/select_union/sqlite/query.sql
+++ b/internal/endtoend/testdata/select_union/sqlite/query.sql
@@ -22,4 +22,4 @@ SELECT * FROM foo;
 -- name: SelectUnionOther :many
 SELECT * FROM foo
 UNION
-SELECT * FROM bar;
\ No newline at end of file
+SELECT * FROM bar;
diff --git a/internal/engine/dolphin/convert.go b/internal/engine/dolphin/convert.go
index 6d95a75064..31d4a70a77 100644
--- a/internal/engine/dolphin/convert.go
+++ b/internal/engine/dolphin/convert.go
@@ -1182,7 +1182,12 @@ func (c *cc) convertSetOprType(n *pcast.SetOprType) (op ast.SetOperation, all bo
 func (c *cc) convertSetOprSelectList(n *pcast.SetOprSelectList) ast.Node {
 	selectStmts := make([]*ast.SelectStmt, len(n.Selects))
 	for i, node := range n.Selects {
-		selectStmts[i] = c.convertSelectStmt(node.(*pcast.SelectStmt))
+		switch node := node.(type) {
+		case *pcast.SelectStmt:
+			selectStmts[i] = c.convertSelectStmt(node)
+		case *pcast.SetOprSelectList:
+			selectStmts[i] = c.convertSetOprSelectList(node).(*ast.SelectStmt)
+		}
 	}
 
 	op, all := c.convertSetOprType(n.AfterSetOperator)