查询专栏:建议使用LambdaQueryWrapper,防误写
/**
* 这样写的好处防误写
*/
@Test
public void selectLambda() {
// LambdaQueryWrapper<User> lambda = new QueryWrapper<User>().lambda();
// LambdaQueryWrapper<User> lambdaQueryWrapper = new LambdaQueryWrapper<>();
LambdaQueryWrapper<User> lambdaQuery = Wrappers.<User>lambdaQuery();
lambdaQuery.like(User::getName, "雨")
.lt(User::getAge, 40);
List<Object> userList = userMapper.selectObjs(lambdaQuery);
userList.forEach(System.out::println);
}
/**
* 5. 名字为王姓并且(年龄小于40或者邮箱不为空)
* sql:name like '王%' and (age < 40 or email is not null)
*/
@Test
public void selectLambda2() {
LambdaQueryWrapper<User> lambdaQuery = Wrappers.<User>lambdaQuery();
lambdaQuery.likeRight(User::getName, "雨")
.lt(User::getAge, 40)
.isNotNull(User::getEmail);
List<Object> userList = userMapper.selectObjs(lambdaQuery);
userList.forEach(System.out::println);
}
@Test
public void selectLambda3() {
List<User> userList = new LambdaQueryChainWrapper<User>(userMapper)
.like(User::getName, "雨")
.ge(User::getAge, 20)
.list();
userList.forEach(System.out::println);
}
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