modify test case

tests/pytest/functions/function_derivative.py

@@ -29,7 +29,6 @@ class TDTestCase:
 
     def insertAndCheckData(self):
         types = ["tinyint", "tinyint unsigned", "smallint", "smallint unsigned", "int", "int unsigned", "bigint", "bigint unsigned", "float", "double", "bool", "binary(20)", "nchar(20)"]
-
         for type in types:
             print("============== create table using %s type ================" % type)
             tdSql.execute("drop table if exists stb")
@@ -68,9 +67,9 @@ class TDTestCase:
                 tdSql.checkData(0, 0, "2018-09-17 09:00:10.000")
                 tdSql.checkData(0, 1, "2018-09-17 09:00:10.000")
                 tdSql.checkData(0, 3, "2018-09-17 09:00:10.000")
-                tdSql.checkData(1, 0, "2018-09-17 09:00:20.009")
-                tdSql.checkData(1, 1, "2018-09-17 09:00:20.009")
-                tdSql.checkData(1, 3, "2018-09-17 09:00:20.009")
+                tdSql.checkData(1, 0, "2018-09-17 09:00:20.000")
+                tdSql.checkData(1, 1, "2018-09-17 09:00:20.000")
+                tdSql.checkData(1, 3, "2018-09-17 09:00:20.000")
 
                 tdSql.query("select ts from(select ts,derivative(col, 10s, 0) from stb group by tbname)")