mybatis sql 语法更新值设置为null
时间: 2024-05-13 11:16:46 浏览: 155
在 MyBatis 中,可以使用 `<if>` 标签来实现动态 SQL,包括设置更新值为 NULL。具体实现步骤如下:
1.在 update 语句中使用 `<set>` 标签,用于指定要更新的列及其对应的值。
2.在 `<set>` 标签中使用 `<if>` 标签,用于判断是否需要更新该列的值。如果需要更新,则设置对应的值为 NULL,否则不设置。
示例代码如下:
```
<update id="updateUser">
UPDATE user
<set>
<if test="name != null">
name = #{name},
</if>
<if test="age != null">
age = #{age},
</if>
<if test="address != null">
address = #{address},
</if>
<if test="phone != null">
phone = #{phone},
</if>
<if test="email != null">
email = #{email},
</if>
<if test="description != null">
description = #{description},
</if>
...
</set>
WHERE id = #{id}
</update>
```
在上面的代码中,如果某个属性值为 null,那么对应的列就不会被更新。如果需要将某个属性设置为 NULL,可以在对应的 `<if>` 标签中使用 `NULL` 关键字,如下所示:
```
<if test="name == null">
name = NULL,
</if>
```
阅读全文
相关推荐

















