MyBatis中的limit分頁設置

更新時間：2023年11月24日 17:05:32 作者：timchen525

這篇文章主要介紹了MyBatis中的limit分頁設置方式,具有很好的參考價值,希望對大家有所幫助,如有錯誤或未考慮完全的地方,望不吝賜教

MyBatis limit分頁設置

錯誤的寫法

<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};  // 錯誤
</select>

在MyBatis中LIMIT之后的語句不允許的變量不允許進行算數運算，會報錯。

正確的寫法一

<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}; （正確）
</select>

正確的寫法二：（推薦）

<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}; （推薦，代碼層可控）
</select>

分析：

方法二的寫法，需要再請求參數中額外設置兩個get函數，如下：

@Data
public class QueryParameterVO {
 
    private List<String> ids;
 
    private List<Integer> statusList;
 
    // 前端傳入的頁碼
    private int pageNo;  // 從1開始
 
    // 每頁的條數
    private int pageSize;
 
    // 數據庫的偏移
    private int offSet;
 
    // 數據庫的大小限制
    private int limit;
 
    // 這里重寫offSet和limit的get方法
    public int getOffSet() {
        return (pageNo-1)*pageSize;
    }
 
    public int getLimit() {
        return pageSize;
    }
}