如何使数字字段不接受负值 [英] how to make numeric field not accept negative value

问题描述

如果更新字段如

它有10.0



现在我减少了11.0

它不会更新它

and if update the field like
it has 10.0

nd now i reduce it by 11.0
it will not update it

推荐答案

检查约束 [ ^ ]



编辑

------------------------

更新前，检查计算是否产生负值。如果为负，则引发异常，否则进行更新。下面的示例。

这里我们在更新前检查StockQty

CHECK Constraint[^]

EDIT
------------------------
Before update, check the calculation produces the negative value or not. If negative, raise exception else do update. Sample below.
Here we're checking the StockQty before update

SET @StockQty = SELECT StockQty FROM TblStock WHERE ItemID = 'SomeItemID';

IF @StockQty < @RequiredQty -- @RequiredQty value from your code as parameter to stored procedure
BEGIN
     PRINT 'Stock Qty is less than Required Qty' --Add exception block here based on your requirement
END
ELSE
BEGIN
     UPDATE TblStock SET StockQty=StockQty-@RequiredQty WHERE ItemID = 'SomeItemID';
END 

通过上述相同的逻辑，您可以在前端执行此操作。

By the above same logic, you could do this in front end.

只检查（当前值） - （新值）> = 0然后更新else什么都不做

just check if the (current value) - (new value) >= 0 then update else do nothing

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