IF条件不适用于条件

Question

我正在尝试下面查询条件是否正常

SELECT SUM(quantity) as qty 
FROM hud_allotment 
where IF (dvn_cd='$q') and IF(to_dvn='$q');  

请告诉我

Answer 1

如果可以使用where and

完成，则不需要

SELECT SUM(quantity) as qty 
FROM hud_allotment 
where dvn_cd='$q' and to_dvn='$q';