多表查询 ,算其中几个字段的总和,该如何解决

多表查询 ,算其中几个字段的总和

SQL code

SELECT a.Id, a.Name, b.C1, b.C2FROM NoverlName AS a INNER JOIN      Click AS b ON a.Id = b.Nid AND b.Year = 2012 AND b.Mon = 3

SQL code

SELECT a.Id, a.Name, b.C1, b.C2，sum(b.C1+b.c2) as totalFROM NoverlName AS a INNER JOIN Click AS b ON a.Id = b.Nid AND b.Year = 2012 AND b.Mon = 3group by a.Id, a.Name, b.C1, b.C2