一、MyBatis Plus 在復雜查詢條件Where中加括號,多個查詢條件在括號內
使用and()
方法
官方給出示例:
and(i -> i.eq("name", "李白").ne("status", "活着")) ---> sql輸出結果:and (name = '李白' and status <> '活着')
二、QueryWrapper
無條件時
1 QueryWrapper<Demo> queryWrapper = new QueryWrapper<>(); 2 queryWrapper.and(query -> query.like(StringUtils.isNotBlank(demo.getName()), "demo.name", demo.getName()).or(). 3 like(StringUtils.isNotBlank(demo.getFrontId()), "demo.frontId", demo.getFrontId())); 4 5 ------> sql輸出結果: 6 select id, name, frontId from demo where ( turbine.name LIKE '%測%' OR turbine.frontId LIKE '%測%')
三、QueryWrapper有條件時
1 QueryWrapper<Demo> queryWrapper = new QueryWrapper<>(); 2 queryWrapper.eq("id",demo.getId); 3 queryWrapper.and(query -> query.like(StringUtils.isNotBlank(demo.getName()), "demo.name", demo.getName()).or(). 4 like(StringUtils.isNotBlank(demo.getFrontId()), "demo.frontId", demo.getFrontId())); 5 6 ------> sql輸出結果: 7 select id, name, frontId from demo where id = 1 and ( turbine.name LIKE '%測%' OR turbine.frontId LIKE '%測%')
四、理解MyBatis Plus
的and()
方法
- 如果
QueryWrapper
對象沒有查詢條件,則只會在where語句中添加()
- 如果
QueryWrapper
對象中有查詢條件了,會在where語句中自動添加and(查詢條件)
五:基於queryWrapper實現分頁查詢
LambdaQueryWrapper<> queryWrapper = new LambdaQueryWrapper<>(); queryWrapper.like(StringUtils.isNoneBlank(rectificationActivityInfo.getActivityName()),RectificationActivityInfo::getActivityName,rectificationActivityInfo.getActivityName()); queryWrapper.eq(StringUtils.isNoneBlank(rectificationActivityInfo.getStatus()),RectificationActivityInfo::getStatus,rectificationActivityInfo.getStatus()); IPage<RectificationActivityInfo> page1 = this.page(page, queryWrapper);
六:lambdaQueryWrapper 基於復雜sql的使用;
1 LambdaQueryWrapper<CarInfo> wrapper = new LambdaQueryWrapper<>(); 2 wrapper.eq(CarInfo::getUsername,username); 3 wrapper.and(StringUtils.isBlank(VIN),x->x.eq(CarInfo::getVinNum,VIN).or(StringUtils.isBlank(autoSN),query->query.eq(CarInfo::getMachineNum,VIN))); 4
七、手寫sql
八、mybaties的select and or查詢
queryWrapper.eq("id", Id); queryWrapper.and(wrapper -> wrapper.eq("expire_time", 0) .or() .gt("expire_time",System.currentTimeMillis() / 1000) ); queryWrapper.select("sum(point) as point, sum(valid_points) as valid_points"); StudentDo studentDo = studentMapper.selectOne(queryWrapper); ===================================輸出sql SELECT sum(point) as point, sum(valid_points) as valid_points from student where id = "111" and (expire_time = 0 or expire_time > "2555")
九.lambdaQueryWrapper基於select字段的查詢
LambdaQueryWrapper<MdmCountry> wrapper1 = new LambdaQueryWrapper<>(); wrapper1.eq(MdmCountry::getCountryCode,countrycode); wrapper1.select(MdmCountry::getCountryCode,MdmCountry::getCountryName,MdmCountry::getAreaId,MdmCountry::getAreaName,MdmCountry::getNationalCompanyId,MdmCountry::getNationalCompanyName); List<MdmCountry> mdmCountries = mdmCountryMapper.selectList(wrapper1);