test: error message when execute DDL under system databases

tests/parallel_test/cases.task

@@ -490,6 +490,7 @@
 ,,y,system-test,./pytest.sh python3 ./test.py -f 1-insert/test_td29793.py
 ,,y,system-test,./pytest.sh python3 ./test.py -f 1-insert/insert_timestamp.py
 ,,y,system-test,./pytest.sh python3 ./test.py -f 1-insert/test_td29157.py
+,,y,system-test,./pytest.sh python3 ./test.py -f 1-insert/ddl_in_sysdb.py
 ,,y,system-test,./pytest.sh python3 ./test.py -f 0-others/show.py
 ,,y,system-test,./pytest.sh python3 ./test.py -f 0-others/show_tag_index.py
 ,,y,system-test,./pytest.sh python3 ./test.py -f 0-others/information_schema.py

tests/system-test/1-insert/ddl_in_sysdb.py

@@ -0,0 +1,43 @@
+import taos
+import sys
+import datetime
+import inspect
+import random
+from util.dnodes import TDDnode
+from util.dnodes import tdDnodes
+
+from util.log import *
+from util.sql import *
+from util.cases import *
+
+class TDTestCase:
+    def init(self, conn, logSql, replicaVar=1):
+        self.replicaVar = int(replicaVar)
+        tdLog.debug(f"start to excute {__file__}")
+        tdSql.init(conn.cursor(), True)
+
+        self.testcasePath = os.path.split(__file__)[0]
+        self.testcasePath = self.testcasePath.replace('\\', '//')
+        self.sysdb = "information_schema"
+
+    def test_ddl(self):
+        tdSql.execute(f"use {self.sysdb}")
+        tdSql.error(f'create stable ins_test (ts timestamp, a int) tags (b int);', expectErrInfo="Cannot create table of system database", fullMatched=False)
+        tdSql.error(f'create table ins_test (ts timestamp, a int);', expectErrInfo="Cannot create table of system database", fullMatched=False)
+        tdSql.error(f'drop table ins_users;', expectErrInfo="Cannot drop table of system database", fullMatched=False)
+
+    def run(self):
+        tdSql.prepare()
+        
+        startTime_all = time.time()
+        self.test_ddl()
+        endTime_all = time.time()
+        print("total time %ds" % (endTime_all - startTime_all))
+
+    def stop(self):
+        tdSql.close()
+        tdLog.success("%s successfully executed" % __file__)
+        
+
+tdCases.addWindows(__file__, TDTestCase())
+tdCases.addLinux(__file__, TDTestCase())