如何防止创建两个字段的值相同的记录? [英] How to prevent creation of records where the value of two fields is the same?

问题描述

我有下表.

CREATE TABLE people(
first_name VARCHAR(128) NOT NULL,
nick_name VARCHAR(128) NULL
)

我想防止人们在尝试插入时将其昵称与姓氏相同.我不想在任何一列上创建索引，只是为了防止在first_name和nick_name相同的情况下插入记录.

I would like to prevent people from having their nickname be the same as their firstname if they attempt that insertion. I do not want to create an index on either of the columns just a rule to prevent the insertion of records where the first_name and nick_name are the same.

有没有一种方法可以创建规则来防止在first_name等于nick_name的位置插入记录?

Is there a way to create a rule to prevent insertion of records where the first_name would equal the nick_name?

推荐答案

CREATE TRIGGER `nicknameCheck` BEFORE INSERT ON `people` FOR EACH ROW begin
  IF (new.first_name = new.nick_name) THEN
    SET new.nick_name = null;
  END IF;
END

或者您可以将first_name设置为NULL，这将导致SQL错误，并且您可以处理它并显示一些警告.

Or you can set first_name to NULL which will cause SQL error and you can handle it and show some warning.

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