MyBatis limit分页设置

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错误的写法:

<select id="queryMyApplicationRecord" parameterType="MyApplicationRequest" resultMap="myApplicationMap">    SELECT    a.*,    FROM    tb_user a    WHERE 1=1    <if test="ids != null and ids.size()!=0">        AND a.id IN        <foreach collection="ids" item="id" index="index"                 open="(" close=")" separator=",">            #{id}        </foreach>    </if>    <if test="statusList != null and statusList.size()!=0">        AND a.status IN        <foreach collection="statusList" item="status" index="index"                 open="(" close=")" separator=",">            #{status}        </foreach>    </if>    ORDER BY a.create_time desc    LIMIT (#{pageNo}-1)*#{pageSize},#{pageSize};  // 错误</select>

在MyBatis中LIMIT之后的语句不允许的变量不允许进行算数运算,会报错。正确的写法一:

<select id="queryMyApplicationRecord" parameterType="MyApplicationRequest" resultMap="myApplicationMap">    SELECT    a.*,    FROM    tb_user a    WHERE 1=1    <if test="ids != null and ids.size()!=0">        AND a.id IN        <foreach collection="ids" item="id" index="index"                 open="(" close=")" separator=",">            #{id}        </foreach>    </if>    <if test="statusList != null and statusList.size()!=0">        AND a.status IN        <foreach collection="statusList" item="status" index="index"                 open="(" close=")" separator=",">            #{status}        </foreach>    </if>    ORDER BY a.create_time desc    LIMIT ${(pageNo-1)*pageSize},${pageSize}; (正确)</select>

正确的写法二:(推荐)

<select id="queryMyApplicationRecord" parameterType="MyApplicationRequest" resultMap="myApplicationMap">    SELECT    a.*,    FROM    tb_user a    WHERE 1=1    <if test="ids != null and ids.size()!=0">        AND a.id IN        <foreach collection="ids" item="id" index="index"                 open="(" close=")" separator=",">            #{id}        </foreach>    </if>    <if test="statusList != null and statusList.size()!=0">        AND a.status IN        <foreach collection="statusList" item="status" index="index"                 open="(" close=")" separator=",">            #{status}        </foreach>    </if>    ORDER BY a.create_time desc    LIMIT #{offSet},#{limit}; (推荐,代码层可控)</select>

分析:方法二的写法,需要再请求参数中额外设置两个get函数,如下:

@Datapublic class QueryParameterVO {     private List<String> ids;     private List<Integer> statusList;     // 前端传入的页码    private int pageNo;  // 从1开始     // 每页的条数    private int pageSize;     // 数据库的偏移    private int offSet;     // 数据库的大小限制    private int limit;     // 这里重写offSet和limit的get方法    public int getOffSet() {        return (pageNo-1)*pageSize;    }     public int getLimit() {        return pageSize;    }}

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