Mybatis中limit用法与分页查询

时间:2025-04-11 18:15:49

错误示范

错误示范一:
<select  resultType="map">
		SELECT <include ref/>
		FROM sys_inspection_form  WHERE
		<if test=" type == 'admin'.toString() ">
			dept_id = #{deptid}
			order by id
			limit  #{start},#{pageSize}
		</if>
		<if test=" type != 'admin'.toString() ">
			dept_id = #{deptid}
			AND status='已发布'
			or user_id = #{userid}
			order by id
			limit  #{start},#{pageSize}
		</if>
	</select>
错误示范二:
<select  resultType="map">
		SELECT <include ref/>
		FROM sys_inspection_form  WHERE
		<if test=" type == 'admin'.toString() ">
			dept_id = #{deptid}
			order by id
			limit = #{start},#{pageSize}
		</if>
		<if test=" type != 'admin'.toString() ">
			dept_id = #{deptid}
			AND status='已发布'
			or user_id = #{userid}
			order by id
			limit = #{start},#{pageSize}
		</if>
	</select>

这里先要了解一下:

#{}和${}的区别:

#{}表示一个占位符号,通过#{}可以实现preparedStatement向占位符中设置值,自动进行java类型和jdbc类型转换。#{}可以有效防止sql注入。 #{}可以接收简单类型值或pojo属性值。 如果parameterType传输单个简单类型值,#{}括号中可以是value或其它名称。
${}表示拼接sql串,通过${}可以将parameterType 传入的内容拼接在sql中且不进行jdbc类型转换, ${}可以接收简单类型值或pojo属性值,如果parameterType传输单个简单类型值,${}括号中只能是value。

正确写法:

<select  resultType="map">
		SELECT <include ref/>
		FROM sys_inspection_form  WHERE
		<if test=" type == 'admin'.toString() ">
			dept_id = #{deptid}
			order by id
			limit  ${start},${pageSize}
		</if>
		<if test=" type != 'admin'.toString() ">
			dept_id = #{deptid}
			AND status='已发布'
			or user_id = #{userid}
			order by id
			limit  ${start},${pageSize}
		</if>
	</select>