1.多条数据查询

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
@Service("xxService")
public class xxServiceImpl extends ServiceImpl<xxDao, xxEntity> implements xxService {
    @Override
    public List<IndexEntity> getList(Map<String, Object> params) {
        List<IndexEntity> list = this.list(
                new QueryWrapper<IndexEntity>()
                        .eq("to_date(STATIS_DATE, 'yyyy-mm-dd')",params.get("statisDate"))
                        .lambda()
                        .eq(StringUtils.isNotBlank(params.get("Type").toString()),IndexEntity::getType,params.get("Type"))
                        .apply(  params.containsKey("insertTimeStart")," INSERT_TIME  BETWEEN  to_date('"+params.get("insertTimeStart")+"', 'yyyy-mm-dd') AND to_date('"+params.get("insertTimeEnd")+"', 'yyyy-mm-dd')")
                        .like(  params.containsKey("province"),"PROVINCE",params.get("province"))
                        .isNotNull("INDEX_ID")
                        .orderByAsc("create_time")
        );
        return list;
    }

2.select指定字段

    @Override
    public PageUtils queryPage(Map<String, Object> params) throws ParseException {
        IPage<CUserEntity> page = this.page(
                new Query<CUserEntity>().getPage(params),
                new QueryWrapper<CUserEntity>()
                        .select("to_char(STATIS_DATE, 'yyyy-MM-dd HH24:mi:ss') as statisDate"," id as ","xxx as ss","xx as ss")
                        .apply(null!=params.get("statisDateStart")," STATIS_DATE  BETWEEN  to_date('"+params.get("statisDateStart")+"', 'yyyy-MM-dd HH24:mi:ss') AND to_date('"+params.get("statisDateEnd")+"', 'yyyy-MM-dd HH24:mi:ss')")
                        .orderByAsc("STATIS_DATE")
        );
        return new PageUtils(page);
    }

3.为读xml文件的sql添加ipage页面

   IPage<Map<String,Object>> relationInfoPage(Map<String, Object> params);

@Mapper
public interface xxDao extends BaseMapper<xxEntity> {
    IPage<Map<String,Object>> relationInfoPage(IPage<Map<String,Object>> page , String Id);
}

    @Override
    public IPage<Map<String, Object>> relationInfoPage(Map<String, Object> params) {
        IPage<Map<String, Object>> thIPage = new Query<Map<String, Object>>().getPage(params);
        return cxDao.relationInfoPage(thIPage,params.get("xId").toString());
    }

若数据库为oralce获取的参数对象为map时回参全大写，避免大写回参可在mapper xml文件中添加默认resultMap配置，如下：

    <!-- 可根据自己的需求，是否要使用 -->
    <resultMap type="com.z.xxEntity" id="xxMap">
        <result property="xId" column="DIX_ID"/>
        <result property="sceneName" column="SCENE_NAME"/>
        <result property="sceneState" column="SCENE_STATE"/>
    </resultMap>

    <select id="relationInfoPage"   resultMap="xxMap" >
        <![CDATA[
            select *
            from  xxx
            where  a.DIX_ID=  #{Id}
            order by  b.create_time asc
        ]]>
    </select>

4.直接拼接lambdaQueryWrapper的方法

带/不带分页

        LambdaQueryWrapper<ResouseEntity> lambdaQueryWrapper = new LambdaQueryWrapper<>();
        lambdaQueryWrapper.eq(ResouseEntity::getTaskId, taskId);
        IPage<ResouseEntity> iPage = ponCutoverOnuInfoService.page(new Query<ResouseEntity>().getPage(params), lambdaQueryWrapper);
//        List<ResouseEntity> list = ponCutoverOnuInfoService.list(lambdaQueryWrapper);
        log.info("查询业务设计结束：" + JSON.toJSONString(iPage));
        return R.ok().put("data", iPage);