mapper.xml中 使用find_in_set
时间: 2024-05-01 11:03:03 浏览: 10
使用`find_in_set`函数可以方便地在逗号分隔的字符串中查找某个值是否存在,其语法如下:
```
FIND_IN_SET(str, strlist)
```
其中,`str`表示要查找的值,`strlist`表示逗号分隔的字符串。
在`mapper.xml`中使用该函数可以像下面这样:
```xml
<select id="getUserByRole" parameterType="string" resultType="User">
SELECT * FROM user WHERE FIND_IN_SET(#{role}, roles)
</select>
```
其中,`#{role}`表示传入的角色名称,`roles`是存储用户角色的字段名。该语句将返回所有角色包含传入角色名称的用户信息。
相关问题
在MybatisPLus中使用find_in_set的用法
在 MybatisPlus 中使用 find_in_set 函数可以通过以下方式实现:
1. 在 xml 映射文件中编写 SQL 语句,使用 CONCAT 和 GROUP_CONCAT 组合起待匹配字符串。
<select id="findInSet" resultType="java.lang.Integer">
SELECT COUNT(*)
FROM table_name
WHERE FIND_IN_SET(#{matchValue}, CONCAT(column_name, ',', GROUP_CONCAT(match_column_name)))
</select>
2. 在对应的 Mapper 接口中声明对应的方法。
@Mapper
public interface TableMapper extends BaseMapper<TableEntity> {
@Select("SELECT COUNT(*) FROM table_name WHERE FIND_IN_SET(#{matchValue}, CONCAT(column_name, ',', GROUP_CONCAT(match_column_name)))")
Integer findInSet(@Param("matchValue") String matchValue);
}
其中,#{matchValue} 表示待匹配的字符串。需要注意的是,如果字符串中含有逗号,需要进行分隔符的转义处理。
mybatis FIND_IN_SET
MyBatis is a popular Java-based persistence framework that provides an object-relational mapping (ORM) solution. It simplifies database interactions by eliminating the need for writing raw SQL queries manually.
Regarding your question about `FIND_IN_SET`, it is a MySQL function that searches for a value within a comma-separated list. However, MyBatis does not have direct support for `FIND_IN_SET` as it focuses on providing a simple and intuitive mapping between Java objects and database tables.
To use `FIND_IN_SET` with MyBatis, you can write a custom query using the `<script>` tag within the XML mapper file. Here's an example:
```xml
<select id="findInSetExample" parameterType="String" resultType="YourResultType">
SELECT * FROM your_table
WHERE
<if test="yourValue != null">
FIND_IN_SET(#{yourValue}, your_column) > 0
</if>
</select>
```
In this example, `your_table` is the name of the table you want to query, `yourValue` is the value you are looking for, and `your_column` is the column containing the comma-separated list. Adjust these placeholders according to your specific use case.
Remember to include the necessary MyBatis configuration and mappers to enable the execution of this query.