diff --git a/src/client/src/tscSQLParser.c b/src/client/src/tscSQLParser.c
index 70495e11ba0f8b3e5bab09c0c3abc8d48b2ce2c2..af9f13df4e5c533a46c2610f000e7c72ef55f741 100644
--- a/src/client/src/tscSQLParser.c
+++ b/src/client/src/tscSQLParser.c
@@ -8277,7 +8277,9 @@ static int32_t doValidateSubquery(SSqlNode* pSqlNode, int32_t index, SSqlObj* pS
 
   // union all is not support currently
   SSqlNode* p = taosArrayGetP(subInfo->pSubquery, 0);
-
+  if (taosArrayGetSize(subInfo->pSubquery) >= 2) {
+    return invalidOperationMsg(msgBuf, "not support union in subquery");
+  }
   SQueryInfo* pSub = calloc(1, sizeof(SQueryInfo));
   tscInitQueryInfo(pSub);
 
diff --git a/tests/pytest/query/nestquery_last_row.py b/tests/pytest/query/nestquery_last_row.py
index a04cb173af25a5cb1b02cb7227f13426503d080e..3c4ada51744f620ca589266113acf1e3d8cfef43 100644
--- a/tests/pytest/query/nestquery_last_row.py
+++ b/tests/pytest/query/nestquery_last_row.py
@@ -160,22 +160,23 @@ class TDTestCase:
         tdSql.checkData(0,9,9.000000000)
         tdSql.checkData(0,10,'2020-09-13 20:26:40.009')
 
+        # incorrect result, not support nest > 2
         sql = '''select last_row(*) from 
                 ((select * from table_0) union all
                  (select * from table_1) union all
                  (select * from table_2));'''
-        tdSql.query(sql)
-        tdSql.checkRows(1)
-        tdSql.checkData(0,1,self.num-1)
-        tdSql.checkData(0,2,self.num-1)
-        tdSql.checkData(0,3,self.num-1)
-        tdSql.checkData(0,4,self.num-1)
-        tdSql.checkData(0,5,'False')
-        tdSql.checkData(0,6,'binary.9')
-        tdSql.checkData(0,7,'nchar.9')
-        tdSql.checkData(0,8,9.00000)
-        tdSql.checkData(0,9,9.000000000)
-        tdSql.checkData(0,10,'2020-09-13 20:26:40.009')
+        tdSql.error(sql)
+        #tdSql.checkRows(1)
+        #tdSql.checkData(0,1,self.num-1)
+        #tdSql.checkData(0,2,self.num-1)
+        #tdSql.checkData(0,3,self.num-1)
+        #tdSql.checkData(0,4,self.num-1)
+        #tdSql.checkData(0,5,'False')
+        #tdSql.checkData(0,6,'binary.9')
+        #tdSql.checkData(0,7,'nchar.9')
+        #tdSql.checkData(0,8,9.00000)
+        #tdSql.checkData(0,9,9.000000000)
+        #tdSql.checkData(0,10,'2020-09-13 20:26:40.009')
 
         # bug 5055
         # sql = '''select last_row(*) from 
@@ -189,18 +190,18 @@ class TDTestCase:
                 ((select last_row(*) from table_0) union all
                  (select last_row(*) from table_1) union all
                  (select last_row(*) from table_2));'''
-        tdSql.query(sql)
-        tdSql.checkRows(1)
-        tdSql.checkData(0,1,self.num-1)
-        tdSql.checkData(0,2,self.num-1)
-        tdSql.checkData(0,3,self.num-1)
-        tdSql.checkData(0,4,self.num-1)
-        tdSql.checkData(0,5,'False')
-        tdSql.checkData(0,6,'binary.9')
-        tdSql.checkData(0,7,'nchar.9')
-        tdSql.checkData(0,8,9.00000)
-        tdSql.checkData(0,9,9.000000000)
-        tdSql.checkData(0,10,'2020-09-13 20:26:40.009')
+        tdSql.error(sql)
+        #tdSql.checkRows(1)
+        #tdSql.checkData(0,1,self.num-1)
+        #tdSql.checkData(0,2,self.num-1)
+        #tdSql.checkData(0,3,self.num-1)
+        #tdSql.checkData(0,4,self.num-1)
+        #tdSql.checkData(0,5,'False')
+        #tdSql.checkData(0,6,'binary.9')
+        #tdSql.checkData(0,7,'nchar.9')
+        #tdSql.checkData(0,8,9.00000)
+        #tdSql.checkData(0,9,9.000000000)
+        #tdSql.checkData(0,10,'2020-09-13 20:26:40.009')
 
         # bug 5055
         # sql = '''select last_row(*) from 
@@ -214,18 +215,18 @@ class TDTestCase:
                 ((select * from table_0 limit 5 offset 5) union all
                  (select * from table_1 limit 5 offset 5) union all
                  (select * from regular_table_1 limit 5 offset 5));'''
-        tdSql.query(sql)
-        tdSql.checkRows(1)
-        tdSql.checkData(0,1,self.num-1)
-        tdSql.checkData(0,2,self.num-1)
-        tdSql.checkData(0,3,self.num-1)
-        tdSql.checkData(0,4,self.num-1)
-        tdSql.checkData(0,5,'False')
-        tdSql.checkData(0,6,'binary.9')
-        tdSql.checkData(0,7,'nchar.9')
-        tdSql.checkData(0,8,9.00000)
-        tdSql.checkData(0,9,9.000000000)
-        tdSql.checkData(0,10,'2020-09-13 20:26:40.009')
+        tdSql.error(sql)
+        #tdSql.checkRows(1)
+        #tdSql.checkData(0,1,self.num-1)
+        #tdSql.checkData(0,2,self.num-1)
+        #tdSql.checkData(0,3,self.num-1)
+        #tdSql.checkData(0,4,self.num-1)
+        #tdSql.checkData(0,5,'False')
+        #tdSql.checkData(0,6,'binary.9')
+        #tdSql.checkData(0,7,'nchar.9')
+        #tdSql.checkData(0,8,9.00000)
+        #tdSql.checkData(0,9,9.000000000)
+        #tdSql.checkData(0,10,'2020-09-13 20:26:40.009')
 
 
         sql = '''select last_row(*)  from 
@@ -260,4 +261,4 @@ class TDTestCase:
 
 
 tdCases.addWindows(__file__, TDTestCase())
-tdCases.addLinux(__file__, TDTestCase())
\ No newline at end of file
+tdCases.addLinux(__file__, TDTestCase())