Hi，大家好，我是编程小6，很荣幸遇见你，我把这些年在开发过程中遇到的问题或想法写出来，今天说一说
mybatisplus分页查询原理_oracle数据库分页,希望能够帮助你!!!。

自定义sql分页的步骤

1. Dao层定义查询接口，第一个参数必须为分页的参数Ipage，后面可带其他参数作为传入参数
2. 定义自定义查询sql

网上很多博客里面写的多表sql分页查询没带参数，这里给一个带参数的列子

JAVA和xml文件如下：

myPageList为使用mybatisPlus写的，pageList和pageListCount为原始写法

可以看出myPageList跟pageListsql语句一模一样，只是第一个参数必须为Ipage

public interface WfPurchaseFrameDao extends SuperDao<WfPurchaseFrame> { List<WfPurchaseFrame> pageList(@Param("param") WfPurchaseFrameParam param); IPage<WfPurchaseFrame> myPageList(IPage<WfPurchaseFrame> page ,@Param("param") WfPurchaseFrameParam param); long pageListCount(@Param("param") WfPurchaseFrameParam param); }

<?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"> <mapper namespace="com.tongtech.biz.purchase.frame.dao.WfPurchaseFrameDao"> <select id="pageList" parameterType="com.tongtech.biz.purchase.frame.model.dto.WfPurchaseFrameParam" resultType="com.tongtech.biz.purchase.frame.model.domain.WfPurchaseFrame"> select t.*,inst.proc_inst_id processInstanceId from t_wf_purchase_frame t left join t_flow_inst inst on inst.business_id = t.apply_id where t.`status` = '0' and inst.proc_inst_status ='1' <if test="param.applyPerson != null and param.applyPerson != ''"> and t.apply_person like concat('%',#{param.applyPerson},'%') </if> <if test="param.projectCode != null and param.projectCode != ''"> and t.project_code like concat('%',#{param.projectCode},'%') </if> <if test="param.projectName != null and param.projectName != ''"> and t.project_name like concat('%',#{param.projectName},'%') </if> limit #{param.page},#{param.limit} </select> <select id="myPageList" parameterType="com.tongtech.biz.purchase.frame.model.dto.WfPurchaseFrameParam" resultType="com.tongtech.biz.purchase.frame.model.domain.WfPurchaseFrame"> select t.*,inst.proc_inst_id processInstanceId from t_wf_purchase_frame t left join t_flow_inst inst on inst.business_id = t.apply_id where t.`status` = '0' and inst.proc_inst_status ='1' <if test="param.applyPerson != null and param.applyPerson != ''"> and t.apply_person like concat('%',#{param.applyPerson},'%') </if> <if test="param.projectCode != null and param.projectCode != ''"> and t.project_code like concat('%',#{param.projectCode},'%') </if> <if test="param.projectName != null and param.projectName != ''"> and t.project_name like concat('%',#{param.projectName},'%') </if> </select> <select id="pageListCount" parameterType="com.tongtech.biz.purchase.frame.model.dto.WfPurchaseFrameParam" resultType="long"> select count(1) from t_wf_purchase_frame t left join t_flow_inst inst on inst.business_id = t.apply_id where t.`status` = '0' and inst.proc_inst_status ='1' <if test="param.applyPerson != null and param.applyPerson != ''"> and t.apply_person like concat('%',#{param.applyPerson},'%') </if> <if test="param.projectCode != null and param.projectCode != ''"> and t.project_code like concat('%',#{param.projectCode},'%') </if> <if test="param.projectName != null and param.projectName != ''"> and t.project_name like concat('%',#{param.projectName},'%') </if> </select> </mapper>

调用 controller层 【省略Service部分】：这里只需要在调用时传递一个Page(long current, long size)即可

@PostMapping(value = "/pageList") public BaseResponse<BaseResponseList<WfPurchaseFrame>> pageList(@RequestBody WfPurchaseFrameParam param){ BaseResponse<BaseResponseList<WfPurchaseFrame>>baseResponse=new BaseResponse<>(); Long page= StringHelper.isEmpty(param.getPage())?BizConstants.PAGE:Long.valueOf(param.getPage()); Long limit= StringHelper.isEmpty(param.getLimit())?BizConstants.LIMIT:Long.valueOf(param.getLimit()); Page<WfPurchaseFrame> resultPage=new Page<>(page,limit); // 这里不能使用QueryWrapper 来传递自定义参数 QueryWrapper<WfPurchaseFrame> queryWrapper=this.createQuery(param); IPage<WfPurchaseFrame> resultList= wfPurchaseFrameService.myPageList(resultPage,param); BaseResponseList<WfPurchaseFrame> baseResponseList=new BaseResponseList<>(); baseResponseList.setData(resultList.getRecords()); baseResponseList.setTotal(resultList.getTotal()); baseResponse.setData(baseResponseList); return baseResponse; }

上面代码中说了不能使用wrapper查询条件构造器，原因为什么呢

${ew.customSqlSegment} 解析时会自动在前面带上where关键字，并且条件构建时不会带上表别名

今天的分享到此就结束了，感谢您的阅读，如果确实帮到您，您可以动动手指转发给其他人。