Question

我有一个简单的SQL查询来计算部门（儿童内部）中的所有员工，例如：

With Temp(id) AS
(
        Select d.id From DEPARTMENT d 
    Where d.id = 1 
    UNION ALL
    Select d.id From DEPARTMENT d JOIN Temp te ON d.idDepartment = te.id
)
Select count(*) From 
(
    Select e.id From Employee e Join Temp te On e.idDepartment = te.id
)

但是我给出了一个错误“StackOverflow”，我不知道哪里出错了，你能帮帮我吗？测试用例有一些数据： 表部门：

ID----------departmentName-----------idDepartment(id parent)
1              A                         0
2              B                         1

表员工：

id----------employeeName------------idDepartment
1              E_1                       1
2              E_2                       1
3              E_3                       2

因此，当我在部门（A）中选择Eployee的数量时 - >结果：3，如果B部分 - >结果：1 谢谢！

Answer 1

我认为我的解决方案有效：

create table Department(id int, name varchar(255), idDepartment int);
create table Employee(id int, name varchar(255), idDepartment int);
insert into Department values(1, 'A', 0), (2, 'B', 1);
insert into Employee values(1, 'E1', 1), (2, 'E2', 1), (3, 'E3', 2);
with recursive temp(id) as (
    select 1 union all
    select d.id from temp te 
    inner join Department d on d.idDepartment = te.id
)
select count(*) from temp te 
inner join Employee e on e.idDepartment = te.id;
drop table Department;
drop table Employee;

在H2DB中使用WITH-CLAUSE进行子查询

1 个答案: