diff --git a/tests/system-test/2-query/explain.py b/tests/system-test/2-query/explain.py
index b452da0a355f0731f8f0e07afd66bb2da86b6761..9694498eb560b3dd3f7a05f0c89dabc912d94a24 100644
--- a/tests/system-test/2-query/explain.py
+++ b/tests/system-test/2-query/explain.py
@@ -33,11 +33,10 @@ class TDTestCase:
         tdSql.init(conn.cursor())
 
     def __query_condition(self,tbname):
-        query_condition = [f"cast({col} as bigint)" for col in ALL_COL]
+        query_condition = [f"{tbname}.{col}" for col in ALL_COL]
         for num_col in NUM_COL:
             query_condition.extend(
                 (
-                    f"{tbname}.{num_col}",
                     f"abs( {tbname}.{num_col} )",
                     f"acos( {tbname}.{num_col} )",
                     f"asin( {tbname}.{num_col} )",
@@ -63,18 +62,19 @@ class TDTestCase:
         for char_col in CHAR_COL:
             query_condition.extend(
                 (
-                    f"count({tbname}.{char_col})",
                     f"sum(cast({tbname}.{char_col}) as bigint)",
                     f"max(cast({tbname}.{char_col}) as bigint)",
                     f"min(cast({tbname}.{char_col}) as bigint)",
                     f"avg(cast({tbname}.{char_col}) as bigint)",
                 )
             )
-        # query_condition.extend(
-        #     (
-        #         1010,
-        #     )
-        # )
+        query_condition.extend(
+            (
+                1010,
+                ''' "test1234!@#$%^&*():'><?/.,][}{" ''',
+                "null"
+            )
+        )
 
         return query_condition
 
@@ -126,7 +126,7 @@ class TDTestCase:
     def __single_sql(self, select_clause, from_clause, where_condition="", group_condition=""):
         if isinstance(select_clause, str) and "on" not in from_clause and select_clause.split(".")[0].split("(")[-1] != from_clause.split(".")[0]:
             return
-        return f"select hyperloglog({select_clause}) from {from_clause} {where_condition} {group_condition}"
+        return f"explain select {select_clause} from {from_clause} {where_condition} {group_condition}"
 
     @property
     def __tb_list(self):
@@ -219,11 +219,13 @@ class TDTestCase:
     def __test_error(self):
 
         tdLog.printNoPrefix("===step 0: err case, must return err")
-        tdSql.error( "select hyperloglog() from ct1" )
-        tdSql.error( "select hyperloglog(c1, c2) from ct2" )
-        tdSql.error( "select hyperloglog(1) from ct2" )
-        tdSql.error( f"select hyperloglog({NUM_COL[0]}, {NUM_COL[1]}) from ct4" )
-        tdSql.error( ''' select hyperloglog(['c1 + c1', 'c1 + c2', 'c1 + c3', 'c1 + c4', 'c1 + c5', 'c1 + c6', 'c1 + c7', 'c1 + c8', 'c1 + c9', 'c1 + c10'])
+        tdSql.error( "select hyperloglog(c1) from ct8" )
+        tdSql.error( "explain show databases " )
+        tdSql.error( "explain show stables " )
+        tdSql.error( "explain show tables " )
+        tdSql.error( "explain show vgroups " )
+        tdSql.error( "explain show dnodes " )
+        tdSql.error( '''explain select hyperloglog(['c1 + c1', 'c1 + c2', 'c1 + c3', 'c1 + c4', 'c1 + c5', 'c1 + c6', 'c1 + c7', 'c1 + c8', 'c1 + c9', 'c1 + c10'])
                     from ct1
                     where ['c1 + c1', 'c1 + c2', 'c1 + c3', 'c1 + c4', 'c1 + c5', 'c1 + c6', 'c1 + c7', 'c1 + c8', 'c1 + c9', 'c1 + c10'] is not null
                     group by ['c1 + c1', 'c1 + c2', 'c1 + c3', 'c1 + c4', 'c1 + c5', 'c1 + c6', 'c1 + c7', 'c1 + c8', 'c1 + c9', 'c1 + c10']