基于mybatis-plus QueryWrapper 排序的坑
时间：2022-12-22 09:54:46 | 栏目：JAVA代码 | 点击：次
QueryWrapper排序的坑
大致可以总结成上面的两句话。
条件构造器QueryWrapper
我们再搞几个实例来深入理解下条件构造器QueryWrapper的用法：
案例一
查询姓李的，并且出生日期范围是1993-02-09到1994-04-09的员工
sql实现：
SELECT * FROM t_employee WHERE DATE_FORMAT(birthday,'%Y-%m-%d')>='1993-02-09' AND DATE_FORMAT(birthday,'%Y-%m-%d')<='1994-04-09' AND NAME LIKE '李%'
mp实现：
/**
* 查询姓李的，并且出生日期范围是1993-02-09到1994-04-09的员工
* sql：SELECT * FROM t_employee WHERE DATE_FORMAT(birthday,'%Y-%m-%d')>='1993-02-09' AND DATE_FORMAT(birthday,'%Y-%m-%d')<='1994-04-09' AND NAME LIKE '李%'
*/
@Test
public void selectByQueryWrapper3(){
QueryWrapper<Employee> queryWrapper=new QueryWrapper();
// QueryWrapper<Employee> queryWrapper2=Wrappers.<Employee>query();
queryWrapper.apply("DATE_FORMAT(birthday,'%Y-%m-%d')>={0} and DATE_FORMAT(birthday,'%Y-%m-%d')<={1}","1993-02-09","1994-04-09").likeRight("name","李");
List<Employee> employeeList = employeeMapper.selectList(queryWrapper);
System.out.println(employeeList);
}
案例二
查询姓李的或者邮箱不为空并且是女性的员工
sql实现：
SELECT * FROM t_employee WHERE NAME LIKE '李%' OR (email IS NOT NULL AND gender ='女')
mp实现：
/**
* 查询姓李的或者邮箱不为空并且是女性的员工
* sql：SELECT * FROM t_employee WHERE NAME LIKE '李%' OR (email IS NOT NULL AND gender ='女')
*/
@Test
public void selectByQueryWrapper4(){
QueryWrapper<Employee> queryWrapper=new QueryWrapper();
// QueryWrapper<Employee> queryWrapper2=Wrappers.<Employee>query();
queryWrapper.likeRight("name","李").or(wq->wq.isNotNull("email").eq("gender","女"));
List<Employee> employeeList = employeeMapper.selectList(queryWrapper);
System.out.println(employeeList);
}
案例三
查询姓李的并且邮箱不为空或者是女性的员工
sql实现：
SELECT * FROM t_employee WHERE NAME LIKE '李%' AND (email IS NOT NULL OR gender ='女')
mp实现：
/**
* 查询姓李的并且邮箱不为空或者是女性的员工
* sql：SELECT * FROM t_employee WHERE NAME LIKE '李%' AND (email IS NOT NULL OR gender ='女')
*/
@Test
public void selectByQueryWrapper5(){
QueryWrapper<Employee> queryWrapper=new QueryWrapper();
// QueryWrapper<Employee> queryWrapper2=Wrappers.<Employee>query();
queryWrapper.likeRight("name","李").and(wq->wq.isNotNull("email").or().eq("gender","女"));
List<Employee> employeeList = employeeMapper.selectList(queryWrapper);
System.out.println(employeeList);
}
案例四
查询属于编号1,2,3部门的并且薪水小于等于3500的员工 根据年龄从大到小排序显示
sql实现：
SELECT * FROM t_employee WHERE salary<=3500 AND departmentId IN (1,2,3) ORDER BY birthday ASC
mp实现：
/**
* 查询属于编号1,2,3部门的并且薪水小于等于3500的员工 根据年龄从大到小排序显示
* sql：SELECT * FROM t_employee WHERE salary<=3500 AND departmentId IN (1,2,3) ORDER BY birthday ASC
*/
@Test
public void selectByQueryWrapper6(){
QueryWrapper<Employee> queryWrapper=new QueryWrapper();
// QueryWrapper<Employee> queryWrapper2=Wrappers.<Employee>query();
queryWrapper.likeRight("name","李").and(wq->wq.isNotNull("email").or().eq("gender","女"));
List<Employee> employeeList = employeeMapper.selectList(queryWrapper);
System.out.println(employeeList);
}