add test case

tests/pytest/functions/function_stddev.py

@@ -127,10 +127,13 @@ class TDTestCase:
         tdSql.execute("create table stdtable(ts timestamp, col1 int) tags(loc nchar(64))")
         tdSql.execute("create table std1 using stdtable tags('beijing')")
         tdSql.execute("create table std2 using stdtable tags('shanghai')")
-        tdSql.execute("insert into std1 values(now, 1)")
-        tdSql.execute("insert into std1 values(now, 2);")
-        tdSql.execute("insert into std2 values(now, 1);")
-        tdSql.execute("insert into std2 values(now, 2);")
+        tdSql.execute("create table std3 using stdtable tags('河南')")
+        tdSql.execute("insert into std1 values(now + 1s, 1)")
+        tdSql.execute("insert into std1 values(now + 2s, 2);")
+        tdSql.execute("insert into std2 values(now + 3s, 1);")
+        tdSql.execute("insert into std2 values(now + 4s, 2);")
+        tdSql.execute("insert into std3 values(now + 5s, 4);")
+        tdSql.execute("insert into std3 values(now + 6s, 8);")
         tdSql.query("select stddev(col1) from stdtable group by loc;")
         tdSql.checkData(0, 0, 0.5)
         tdSql.checkData(1, 0, 0.5)
@@ -138,10 +141,10 @@ class TDTestCase:
         tdSql.execute("create table stdtableint(ts timestamp, col1 int) tags(num int)")
         tdSql.execute("create table stdint1 using stdtableint tags(1)")
         tdSql.execute("create table stdint2 using stdtableint tags(2)")
-        tdSql.execute("insert into stdint1 values(now, 1)")
-        tdSql.execute("insert into stdint1 values(now, 2);")
-        tdSql.execute("insert into stdint2 values(now, 1);")
-        tdSql.execute("insert into stdint2 values(now, 2);")
+        tdSql.execute("insert into stdint1 values(now + 1s, 1)")
+        tdSql.execute("insert into stdint1 values(now + 2s, 2);")
+        tdSql.execute("insert into stdint2 values(now + 3s, 1);")
+        tdSql.execute("insert into stdint2 values(now + 4s, 2);")
         tdSql.query("select stddev(col1) from stdtableint group by num")
         tdSql.checkData(0, 0, 0.5)
         tdSql.checkData(1, 0, 0.5)