add test case for join query

tests/pytest/query/queryJoin.py

@@ -121,6 +121,9 @@ class TDTestCase:
         tdSql.query("select stb_t.ts, stb_t.dscrption, stb_t.temperature, stb_t.id, stb_p.dscrption, stb_p.pressure from stb_p, stb_t where stb_p.ts=stb_t.ts and stb_p.id = stb_t.id")
         tdSql.checkRows(6)
 
+        tdSql.query("select stb_t.ts, stb_t.dscrption, stb_t.temperature, stb_t.id, stb_p.dscrption, stb_p.pressure from stb_p, stb_t where stb_p.ts=stb_t.ts and stb_p.id = stb_t.id order by ts desc limit 1 offset 1")
+        tdSql.checkRows(1)
+
         tdSql.error("select stb_t.ts, stb_t.dscrption, stb_t.temperature, stb_t.pid, stb_p.id, stb_p.dscrption, stb_p.pressure,stb_v.velocity from stb_p, stb_t, stb_v where stb_p.ts=stb_t.ts and stb_p.ts=stb_v.ts and stb_p.id = stb_t.id")
 
         # test case for https://jira.taosdata.com:18080/browse/TD-1250