MySQL设置默认ID UUID [英] MySQL set default id UUID

问题描述

我正在尝试在具有id字段的数据库中创建表，默认情况下将使用UUID填充ID.

I'm trying to create tables in a database that has an id field that will populate the id with an UUID by default.

我尝试过类似的事情:

CREATE TABLE FOO (
  id CHAR(36) PRIMARY KEY DEFAULT uuid()
);

非常感谢您的协助.

推荐答案

从5.7开始，MySQL不支持使用函数作为列的默认值.

MySQL as of 5.7 does not support using a function as the default value of a column.

数据类型规范中的DEFAULT value子句指示列的默认值.除了一个例外，默认值必须为常数；否则为0. 它不能是函数或表达式.

https://dev.mysql.com/doc/refman/5.7/zh-CN/data-type-defaults.html

另一种选择是使用触发器来监视所需表的BEFORE INSERT.

The alternative would be to use a trigger to monitor the BEFORE INSERT of the desired table.

DELIMITER ;;
CREATE TRIGGER `foo_before_insert` 
BEFORE INSERT ON `foo` FOR EACH ROW 
BEGIN
  IF new.id IS NULL THEN
    SET new.id = uuid();
  END IF;
END;;
DELIMITER ;

除非已明确定义，否则它将把INSERT语句的默认值更改为uuid()值.

This will change the default value of an INSERT statement to the uuid() value, unless it has been explicitly defined.

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