[英]How do I check before updating the table contents in php with IF Statement in PHP?
如果 <=0 (减号)设置为 0,我如何在使用 IF 语句更新之前检查
$sql="UPDATE tblemployees SET AnnualLeaveRights = 0 (IF(AnnualLeaveRights <=0)) WHERE EmpId=:empid";
非常感谢您的帮助。
不要触摸您不打算更改的行。
$sql= "UPDATE tblemployees
SET AnnualLeaveRights = 0
WHERE EmpId=:empid
AND AnnualLeaveRights < 0";
请执行下列操作:
$sql="UPDATE tblemployees
SET AnnualLeaveRights = IF(AnnualLeaveRights <= 0, 0, AnnualLeaveRights)
WHERE EmpId=:empid";
您也可以改用Greatest()
函数:
$sql="UPDATE tblemployees
SET AnnualLeaveRights = GREATEST(0,AnnualLeaveRights)
WHERE EmpId=:empid";
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