Mybatis-plus使用wrapper多表内连接左连接查询方式

<!--引入MyBatisPlus依赖-->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
            <version>3.4.0</version>
        </dependency>

public interface WReqMstMapper extends BaseMapper<WReqMst>{
@Select("SELECT mst.*,wh1.whname as REQWHNAME,wh2.whname as BYREQWHNAME ,comp.companyname as DEPTNAME FROM w_req_mst mst inner join gen_company comp on mst.deptid=comp.companyid left join gen_wh_def wh1 on mst.reqwhid=wh1.whid inner join gen_wh_def wh2 on mst.byreqwhid=wh2.whid ${ew.customSqlSegment}")
IPage<WReqMst> mlist(IPage<WReqMst> page,@Param(Constants.WRAPPER)Wrapper<WReqMst>wrapper);
}

public interface IWReqMstService extends IService<WReqMst> {
	
	IPage<WReqMst> getPageList(WReqMstListDto pageListDto);
}

@Service
public class WReqMstServiceImpl extends BaseService<WReqMstMapper, WReqMst> implements IWReqMstService {

	private IWReqDtlService wReqDtlService;
	@Resource
	private WReqMstMapper getWReqMstMapper;
	@Override
	public IPage<WReqMst> getPageList(WReqMstListDto pageListDto) {
		Wrapper<WReqMst> wrapper = Wrappers.<WReqMst>query().lambda()
				.like(!StringUtil.isEmpty(pageListDto.getHISREQNO()), WReqMst::getHisreqno, pageListDto.getHISREQNO())
				.ge(!StringUtil.isEmpty(pageListDto.getINPUTDATE_Start()), WReqMst::getInputdate, DateTimeUtil.minForTime(pageListDto.getINPUTDATE_Start(), "datetime"))
				.le(!StringUtil.isEmpty(pageListDto.getINPUTDATE_End()), WReqMst::getInputdate, DateTimeUtil.maxForTime(pageListDto.getINPUTDATE_End(), "datetime"))
				.eq(!StringUtil.isEmpty(pageListDto.getREQTYPE()), WReqMst::getReqtype, pageListDto.getREQTYPE());
		return getWReqMstMapper.mlist(ConventPage.getPage(pageListDto), wrapper);//this.page(ConventPage.getPage(pageListDto), wrapper);
	}
}

@GetMappin
	public Response<PageOutput<WReqMstListVo>> getPageList(WReqMstListDto listDto) {
		IPage<WReqMst> page = wReqMstService.getPageList(listDto);
		List<WReqMstListVo> records = BeanUtil.copyList(page.getRecords(), WReqMstListVo.class);//分页。wrapper自带
		return Response.ok(ConventPage.getPageOutput(page.getTotal(), records));
	}

<resultMap id="wReqMstResultMap" type="WReqMst">
        <id column="REQMSTID" property="reqmstid"/>
        <result column="INPUTDATE" property="inputdate"/>
        <result column="DEPTID" property="deptid"/>
        <result column="REQWHID" property="reqwhid"/>
        <result column="BYREQWHID" property="byreqwhid"/>
        <result column="MEMO" property="memo"/>
        <association property="deptname" column="DEPTID" select="com.xjrsoft.module.customerTwo.AppManage.genCompany.mapper.GenCompanyMapper.selectNameById"/>
        <association property="reqwhname" column="REQWHID" select="com.xjrsoft.module.customerTwo.AppManage.genWh.mapper.GenWhDefMapper.selectNameById"/>
        <association property="byreqwhname" column="BYREQWHID" select="com.xjrsoft.module.customerTwo.AppManage.genWh.mapper.GenWhDefMapper.selectNameById"/>
    </resultMap>

    <select id="wReqMstList" resultMap="wReqMstResultMap">
        select *
        from w_req_mst
    </select>