fix(engine/dolphin): Fixed problem that LIMIT OFFSET cannot be used with UNION ALL (#2613)

* fix(engine/dolphin): Fixed problem that LIMIT OFFSET cannot be used with `UNION ALL`

close #2611

* test: update endtoend

Author: orisano

internal/endtoend/testdata/select_union/mysql/go/query.sql.go

@@ -5,6 +5,12 @@ SELECT * FROM foo
 UNION
 SELECT * FROM foo;
 
+-- name: SelectUnionWithLimit :many
+SELECT * FROM foo
+UNION
+SELECT * FROM foo
+LIMIT ? OFFSET ?;
+
 -- name: SelectExcept :many
 SELECT * FROM foo
 EXCEPT

internal/endtoend/testdata/select_union/mysql/query.sql

@@ -5,6 +5,12 @@ SELECT * FROM foo
 UNION
 SELECT * FROM foo;
 
+-- name: SelectUnionWithLimit :many
+SELECT * FROM foo
+UNION
+SELECT * FROM foo
+LIMIT $1 OFFSET $2;
+
 -- name: SelectExcept :many
 SELECT * FROM foo
 EXCEPT

internal/endtoend/testdata/select_union/postgres/pgx/v4/go/query.sql.go

@@ -5,6 +5,12 @@ SELECT * FROM foo
 UNION
 SELECT * FROM foo;
 
+-- name: SelectUnionWithLimit :many
+SELECT * FROM foo
+UNION
+SELECT * FROM foo
+LIMIT $1 OFFSET $2;
+
 -- name: SelectExcept :many
 SELECT * FROM foo
 EXCEPT

internal/endtoend/testdata/select_union/postgres/pgx/v4/query.sql

@@ -5,6 +5,12 @@ SELECT * FROM foo
 UNION
 SELECT * FROM foo;
 
+-- name: SelectUnionWithLimit :many
+SELECT * FROM foo
+UNION
+SELECT * FROM foo
+LIMIT $1 OFFSET $2;
+
 -- name: SelectExcept :many
 SELECT * FROM foo
 EXCEPT

internal/endtoend/testdata/select_union/postgres/pgx/v5/go/query.sql.go

@@ -1265,7 +1265,12 @@ func (c *cc) convertSetOprSelectList(n *pcast.SetOprSelectList) ast.Node {
 
 func (c *cc) convertSetOprStmt(n *pcast.SetOprStmt) ast.Node {
 	if n.SelectList != nil {
-		return c.convertSetOprSelectList(n.SelectList)
+		sn := c.convertSetOprSelectList(n.SelectList)
+		if ss, ok := sn.(*ast.SelectStmt); ok && n.Limit != nil {
+			ss.LimitOffset = c.convert(n.Limit.Offset)
+			ss.LimitCount = c.convert(n.Limit.Count)
+		}
+		return sn
 	}
 	return todo(n)
 }