在使用MyBatis-Plus时,我们可以通过QueryWrapper
来构建复杂的查询条件,其中可以使用and
和or
来嵌套条件。以下是一个使用and
和or
嵌套条件的例子:
1. and ( ... or ... or...) 格式
import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.extension.service.IService;
// 假设有一个实体类Entity和对应的服务类IService
public class Entity {
private Integer id;
private String name;
private Integer age;
// 省略其他字段、构造函数、getter和setter方法
}
public interface IEntityService extends IService<Entity> {
// 其他业务方法
}
// 使用QueryWrapper构建查询条件
QueryWrapper<Entity> queryWrapper = new QueryWrapper<>();
queryWrapper.eq("name", "Alice") // 外层and条件
.and(i -> i.eq("age", 25).or().eq("age", 30)); // 嵌套and条件,其中包含or条件
// 使用服务类进行查询
List<Entity> result = entityService.list(queryWrapper);
@GetMapping(value = "/list")
public Result<IPage<YwglInfo>> queryPageList(YwglInfo ywglInfo,
@RequestParam(name = "pageNo", defaultValue = "1") Integer pageNo,
@RequestParam(name = "pageSize", defaultValue = "10") Integer pageSize,
HttpServletRequest req) {
QueryWrapper<YwglInfo> queryWrapper = QueryGenerator.initQueryWrapper(ywglInfo, req.getParameterMap());
String kh = req.getParameter("kh");
if (StringUtils.isNotEmpty(kh)){
//原来bug sql
//queryWrapper.eq("send_addr",kh).or().eq("receive_addr",kh);
queryWrapper.and(wrapper -> wrapper.eq("send_addr",kh).or().eq("receive_addr",kh));
}
Page<YwglInfo> page = new Page<YwglInfo>(pageNo, pageSize);
IPage<YwglInfo> pageList = ywglInfoService.page(page, queryWrapper);
return Result.OK(pageList);
}
打印出来的正确SQL如下
send_type = '0'并且(send_addr = '4224' 或者 receive_addr = '4214')
SELECT send_addr, send_type, receive_addr, receive_type,create_time, create_by, state_desc, comm_type, sfsc, send_time
FROM ywglinfo WHERE
(send_type = '0' AND (send_addr = '4224' OR receive_addr = '4214'))
ORDER BY create_time DESC
错误SQL少了括号
send_type = '0'并且send_addr = '4224' 或者 receive_addr = '4214'
SELECT send_addr, send_type, receive_addr, receive_type,create_time, create_by, state_desc, comm_type, sfsc, send_time
FROM ywglinfo WHERE
(send_type = '0' AND send_addr = '4224' OR receive_addr = '4214')
ORDER BY create_time DESC
2. or ( ... and ... and ...) 格式
年纪既不等于6也不等于33
wrapper.or(wrapper -> wrapper.ne("age", 6).ne("age",33);