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分组

通过如下方式可以使用条件构造器构建分组查询。

LambdaTemplate lambda = ...

List<User> result = null;
result = lambda.query(User.class)
               .ge(User::getId, 100)
               .le(User::getId, 500)
               .groupBy(User::getStatus)
               .queryForList();
// result 结果集 User 对象中将只有 status 会有值
对应的 SQL
select status from users where id >= 100 and id <= 500 group by status;

使用聚合函数​

分组求和
class UserGroupBy{
    private String  status;
    private Integer cnt;
    ...
}

LambdaTemplate lambda = ...

List<UserGroupBy> result = null;
result = lambda.query(User.class)
               .ge(User::getId, 100)
               .le(User::getId, 500)
               .groupBy(User::getStatus)
               .selectAdd(User::getStatus)
               .applySelectAdd("count(*) as cnt")
               .queryForList(UserGroupBy.class);
对应的 SQL
select status, count(*) as cnt
from users
where id >= 100 and id <= 500
group by status;