add test cases for leastsquares

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

@@ -219,7 +219,7 @@ class TDTestCase:
             tdSql.checkRows(1)
             res = tdSql.getData(0, 0)
             if res is None:
-                tdLog.exit("result is not correct")        
+                tdLog.exit("result is not correct")
 
     def __test_current(self):
         # tdSql.query("explain select c1 from {dbname}.ct1")
@@ -228,6 +228,11 @@ class TDTestCase:
         # tdSql.query("explain select count(c3) from {dbname}.ct4 group by c7 having count(c3) > 0")
         # tdSql.query("explain select ct2.c3 from {dbname}.ct4 join ct2 on ct4.ts=ct2.ts")
         # tdSql.query("explain select c1 from stb1 where c1 is not null and c1 in (0, 1, 2) or c1 between 2 and 100 ")
+        #
+        tdSql.query("select leastsquares(c1, 1, 1) from (select c1 from nt1 group by c1)")
+        tdSql.query("select leastsquares(c1, 1, 1) from (select c1 from nt1 partition by c1)")
+        tdSql.query("select leastsquares(c1, 1, 1) from (select c1 from nt1 order by c1)")
+        tdSql.query("select leastsquares(c1, 1, 1) from (select c1 from nt1 union select c1 from nt1)")
 
         self.leastsquares_check()