mybatis-plus的${ew.sqlSegment}，${ew.sqlSelect}，${ew.sqlSet}，${ew.customSqlSegment}使用与区别

Posted 2023-03-15 lovoo

说明：

ew是mapper方法里的@Param(Constants.WRAPPER) Wrapper queryWrapper对象

1、$ew.customSqlSegment 会直接在前面添加 where

@Select(select * from sys_user $ew.customSqlSegment）
List<SysUser> listPage(@Param(Constants.WRAPPER)  QueryWrapper queryWrapper)

2、$ew.sqlSegment 就只有条件语句

 @Select(select * from sys_user  where $ew.sqlSegment）
 List<SysUser> listPage@Param(Constants.WRAPPER) QueryWrapper queryWrapper)

3、$ew.sqlSelect 就是 queryWrapper.select(****) 你所定义需要查询的字段

实例1：

@Select(select $ew.sqlSelect from sys_user  ）
List<SysUser> listPage(@Param(Constants.WRAPPER) QueryWrapper queryWrapper)

实例2：

<select id="selectUser" resultType="com.example.demo.entity.User">
        select
            <if test="ew != null and ew.sqlSelect != null and ew.sqlSelect != ''">
                $ew.sqlSelect
            </if>
        from
            sys_user
        where is_deleted != 1
        <if test="ew != null">
            <if test="ew.nonEmptyOfWhere">
                AND
            </if>
            $ew.sqlSegment
        </if>
    </select>

4、$ew.sqlSet用于update语句

boolean updateById(@Param("tableName") String tableName,@Param(Constants.WRAPPER) Wrapper wrapper);

实例1

<update id="updateById">
    update $tableName set $ew.sqlSet $ew.customSqlSegment;
</update>

实例2

<update id="updateUser">
		update sys_user
		set $ew.sqlSet
		where $ew.sqlSegment
    </update>