将最大值设置为一列 [英] set maximum value to a column

问题描述

我有一张表，其中有一个称为age的列(整数类型).该列的最大值应为50.如果超过该最大值，则不应更新该行.

I have a table with a column (int type) called age. This column should hold maximun value 50. If it exceeds then it shouldn't update that row.

表示此列的保留值介于0到50之间.

Means this column shold take values from 0 to 50.

如果我尝试将其更新为51，那应该是不允许的.

If I try to update that to 51 then that shouldn't allow.

任何人都可以帮忙....！

Could any one help....!

推荐答案

尝试一下:

CREATE TRIGGER check_trigger
  BEFORE INSERT
  ON table
  FOR EACH ROW
BEGIN
  IF NEW.age<0 OR NEW.age>50 THEN
    CALL `Error: Wrong values for age`; -- this trick will throw an error
  END IF;
END

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