MybatisPlus自定义Sql实现多表查询的示例

@Data
@AllArgsConstructor
@NoArgsConstructor
public class LayuiData {
  private Integer code=0;
  private Long count;
  private String msg="ok";
  private Object data;
}

@GetMapping("/getClientList")
@ResponseBody
public LayUIResult getAll(
    @RequestParam(name = "page", required = true, defaultValue = "1") int num,
    @RequestParam(name = "limit", required = true, defaultValue = "10") int size,
    String keyWord, String registerTime){
  IPage<Map<String, Object>> listPage = clientService.findClientPage(num, size, keyWord,registerTime);
  //返回总数和数据
  return new LayuiData (listPage.getTotal(),listPage.getRecords());
}

IPage<Map<String, Object>> findClientPage(Integer num, Integer size, String keyWord, String registerTime);

@Override
public IPage<Map<String, Object>> findClientPage(Integer num, Integer size, String keyWord, String registerTime) {
  //创建QueryWrapper搜索对象，判断参数不为空则传入参数
  QueryWrapper<Map<String, Object>> wrapper = new QueryWrapper<>();
  if (StringUtils.isNotEmpty(keyWord)) {
    wrapper.like("c.real_name", keyWord).or().like("c.phone", keyWord);
  }
  if (StringUtils.isNotEmpty(registerTime)) {
    String stime = registerTime.substring(0, 20);
    String etime = registerTime.substring(22, 41);
    wrapper.ge("c.register_time", stime).le("c.register_time", etime);
  }
  //创建分页对象
  Page<Map<String, Object>> page = new Page<>(num, size);

  return clientMapper.findClientPage(page, wrapper);
}

IPage<Map<String, Object>> findClientPage(Page<Map<String, Object>> page,@Param(Constants.WRAPPER) QueryWrapper<Map<String, Object>> wrapper);

<select id="findClientPage" resultType="java.util.Map">
 SELECT c.id,c.real_name,c.phone,c.`status`,
 //实现将时间转换成固定格式
 DATE_FORMAT(c.register_time,'%Y-%m-%d %H:%i:%s') registerTime,
 SUM(re.money) rechargeMoney, SUM(wi.withdrawal_money) withdrawalMoney,SUM(buy_money) orderMoney,
 wa.balance
 FROM client c
 LEFT JOIN recharge re ON c.id=re.client_id
 LEFT JOIN withdrawal wi ON c.id=wi.client_id
 LEFT JOIN wallet wa ON c.id=wa.client_id
 LEFT JOIN order_position ord on c.id=ord.client_id
 //重点是这里会插入wrapper的搜索语句
 ${ew.customSqlSegment}
 GROUP BY c.id
</select>