add test cases

tests/system-test/2-query/interp.py

@@ -38,6 +38,8 @@ class TDTestCase:
 
         tdLog.printNoPrefix("==========step2:insert data")
 
+        tdSql.execute(f"use db")
+
         tdSql.execute(f"insert into {dbname}.{tbname} values ('2020-02-01 00:00:05', 5, 5, 5, 5, 5.0, 5.0, true, 'varchar', 'nchar')")
         tdSql.execute(f"insert into {dbname}.{tbname} values ('2020-02-01 00:00:10', 10, 10, 10, 10, 10.0, 10.0, true, 'varchar', 'nchar')")
         tdSql.execute(f"insert into {dbname}.{tbname} values ('2020-02-01 00:00:15', 15, 15, 15, 15, 15.0, 15.0, true, 'varchar', 'nchar')")