MyBatis：条件构造器QueryWrapper方法详解
Posted csjoz11
tags:
篇首语：本文由小常识网(cha138.com)小编为大家整理，主要介绍了MyBatis：条件构造器QueryWrapper方法详解相关的知识，希望对你有一定的参考价值。
正文
QueryWrapper
说明:
继承自 AbstractWrapper ,自身的内部属性 entity 也用于生成 where 条件
及 LambdaQueryWrapper, 可以通过 new QueryWrapper().lambda() 方法获取.
测试用表：
1. eq、ne
说明：
eq：等于，ne：不等于
测试：
@Test
public void contextLoads(){
QueryWrapper<Employee> wrapper = new QueryWrapper<>();
//eq() 等于
wrapper.eq("last_name", "皮皮虾");
Employee one = employeeService.getOne(wrapper);
System.out.println(one);
}
@Test
public void contextLoads(){
QueryWrapper<Employee> wrapper = new QueryWrapper<>();
//ne() 不等于
wrapper.ne("gender", 0);
List<Employee> list = employeeService.list(wrapper);
System.out.println(list);
}
2. gt、ge、lt、le
说明：
gt：大于，ge：大于等于，lt：小于，le：小于等于
测试：
@Test
public void contextLoads(){
QueryWrapper<Employee> gtWrapper = new QueryWrapper<>();
//gt() 大于
gtWrapper.gt("age", 27);
List<Employee> gtList = employeeService.list(gtWrapper);
System.out.println(gtList);
//**********************
QueryWrapper<Employee> geWrapper = new QueryWrapper<>();
//ge() 大于等于
geWrapper.ge("age", 26);
List<Employee> geList = employeeService.list(geWrapper);
System.out.println(geList);
}
@Test
public void contextLoads(){
QueryWrapper<Employee> ltWrapper = new QueryWrapper<>();
//lt() 小于
ltWrapper.lt("age", 12);
List<Employee> ltList = employeeService.list(ltWrapper);
System.out.println(ltList);
//**********************
QueryWrapper<Employee> geWrapper = new QueryWrapper<>();
//le() 小于等于
leWrapper.le("age", 12);
List<Employee> leList = employeeService.list(leWrapper);
System.out.println(leList);
}
3. between、notBetween
说明：
between：在值1和值2之间，notBetween：不在值1和值2之间
测试：
@Test
public void contextLoads(){
QueryWrapper<Employee> betweenWrapper = new QueryWrapper<>();
//between() 区间的值
betweenWrapper.between("age", 10, 20);
List<Employee> betweenList = employeeService.list(betweenWrapper);
System.out.println(betweenList );
//**********************
QueryWrapper<Employee> notBetweenWrapper = new QueryWrapper<>();
//notBetween() 不在区间的值
notBetweenWrapper.notBetween("age", 10, 21);
List<Employee> notBetweenList = employeeService.list(notBetweenWrapper );
System.out.println(notBetweenList );
}
4. like、notLike、likeLeft、likeRight
说明：
like：’%值%’，notLike：’%值%’，likeLeft：’%值’，likeRight：\'值%\'
测试：
@Test
public void contextLoads(){
QueryWrapper<Employee> likeWrapper = new QueryWrapper<>();
//like() 模糊查询匹配值
likeWrapper.like("last_name", "s");
List<Employee> likeList = employeeService.list(likeWrapper);
System.out.println(likeList );
//**********************
QueryWrapper<Employee> notLikeWrapper = new QueryWrapper<>();
//notLike() 模糊查询不匹配值
notLikeWrapper.notLike("last_name", "s");
List<Employee> notLikeList = employeeService.list(notLikeWrapper);
System.out.println(notLikeList);
}
@Test
public void contextLoads(){
QueryWrapper<Employee> likeLeftWrapper = new QueryWrapper<>();
//likeLeft() 模糊查询匹配最后一位值
likeLeftWrapper.likeLeft("last_name", "s");
List<Employee> likeLeftList = employeeService.list(likeLeftWrapper);
System.out.println(likeLeftList );
//**********************
QueryWrapper<Employee> likeRightWrapper = new QueryWrapper<>();
//likeRight() 模糊查询匹配第一位值
likeRightWrapper.likeRight("last_name", "s");
List<Employee> likeRightList = employeeService.list(likeRightWrapper );
System.out.println(likeRightList );
}
5. isNull、isNotNull
说明：
isNull：字段 IS NULL，isNotNull：字段 IS NOT NULL
测试：
@Test
public void contextLoads(){
QueryWrapper<Employee> isNullWrapper = new QueryWrapper<>();
//isNull() 为空
isNullWrapper.isNull("email");
List<Employee> isNullList = employeeService.list(isNullWrapper);
System.out.println(isNullList );
//**********************
QueryWrapper<Employee> isNotNullWrapper = new QueryWrapper<>();
//isNotNull() 不为空
isNotNullWrapper.isNotNull("last_name", "s");
List<Employee> isNotNullList = employeeService.list(isNotNullWrapper );
System.out.println(isNotNullList );
}
6. in、notIn
说明：
in：字段 IN (v0, v1, …)，notIn：字段 NOT IN (value.get(0), value.get(1), …)
测试：
@Test
public void contextLoads(){
QueryWrapper<Employee> inWrapper = new QueryWrapper<>();
//in() 符合多个条件的值
inWrapper.in("age", 8, 16, 26);
List<Employee> inList = employeeService.list(inWrapper);
System.out.println(inList );
//**********************
QueryWrapper<Employee> notInWrapper= new QueryWrapper<>();
//notIn() 不符合多个条件的值
notInWrapper.notIn("age", 8, 16, 26);
List<Employee> notInList = employeeService.list(notInWrapper);
System.out.println(notInList );
}
7. or、and
说明：
or：或者 ，and：和
注意事项:
主动调用or表示紧接着下一个方法不是用and连接!(不调用or则默认为使用and连接)
测试：
@Test
public void contextLoads(){
QueryWrapper<Employee> orWrapper = new QueryWrapper<>();
//or() 查询age大于20 或者 gender等于1 的数据
orWrapper.gt("age", 20).or().eq("gender", 1);
List<Employee> orList = employeeService.list(orWrapper);
System.out.println(orList );
}
@Test
public void contextLoads(){
QueryWrapper<Employee> andWrapper = new QueryWrapper<>();
//and() 查询last_name等于皮皮虾b 和 gender等于1 的数据 (不使用and() 默认就是and())
andWrapper.eq("last_name", "皮皮虾b").eq("gender", 1);
List<Employee> andList = employeeService.list(andWrapper );
System.out.println(andList);
}
8. orderByAsc、orderByDesc
说明：
orderByAsc：升序：ORDER BY 字段, … ASC，orderByDesc：降序：ORDER BY 字段, … DESC
测试：
@Test
public void contextLoads(){
QueryWrapper<Employee> Wrapper = new QueryWrapper<>();
//orderByAsc() 升序排序
Wrapper.orderByAsc("id");
List<Employee> list = employeeService.list(Wrapper);
for(Employee e : list) {
System.out.println(e);
}
}
@Test
public void contextLoads(){
QueryWrapper<Employee> Wrapper = new QueryWrapper<>();
//orderByDesc() 降序排序
Wrapper.orderByDesc("id");
List<Employee> list = employeeService.list(Wrapper);
for(Employee e : list) {
System.out.println(e);
}
}
9. inSql、notInSql (不常用)
说明：
inSql：字段 IN ( sql语句 )，notInSql：字段 NOT IN ( sql语句 )
测试：
@Test
public void contextLoads(){
QueryWrapper<Employee> inSqlWrapper = new QueryWrapper<>();
//inSql() 符合sql语句的值
inSqlWrapper .inSql("select id from employee where id < 10");
List<Employee> inSqlList = employeeService.list(inSqlWrapper );
System.out.println(inSqlList );
//**********************
QueryWrapper<Employee> notInSqlWrapper= new QueryWrapper<>();
//notInSql() 不符合sql语句的值
notInSqlWrapper.notInSql("select id from employee where id < 10");
List<Employee> notInSqlList = employeeService.list(notInSqlWrapper);
System.out.println(notInSqlList );
}
10. exists、notExists (不常用)
说明：
exists：拼接 EXISTS ( sql语句 )，notExists：拼接 NOT EXISTS ( sql语句 )
测试：
@Test
public void contextLoads(){
QueryWrapper<Employee> existsWrapper = new QueryWrapper<>();
//exists() 查询符合sql语句的值
existsWrapper.exists("select last_name,gender from employee where id = 1");
List<Employee> existsList = employeeService.list(existsWrapper);
System.out.println(existsList );
//**********************
QueryWrapper<Employee> notExistsWrapper = new QueryWrapper<>();
//notExists() 查询不符合sql语句的值
notExistsWrapper.notExists("select last_name,gender from employee where id = 1");
List<Employee> notExistsList = employeeService.list(notExistsWrapper);
System.out.println(notExistsList );
}
文章转载至：https://blog.csdn.net/llllllkkkkkooooo/article/details/108216957