我有2张桌子 1-部门(某些部门是其他部门的一部分) 2名员工,在部门工作
WITH `d1` AS (
SELECT 1 ID, 'dep1' NAME, null Parent_id UNION ALL
SELECT 2, 'dep2', null UNION ALL
SELECT 3, 'dep21', 2 UNION ALL
SELECT 4,'dep22', 2
)
WITH `d2` AS (
SELECT 1 ID, 'Name1' NAME, 3 DEP_id UNION ALL
SELECT 2, 'Name2', 4 UNION ALL
SELECT 3, 'Name3', 1 UNION ALL
SELECT 4, 'Name4', 2 UNION ALL
我需要找到每个部门的员工人数,包括家长。我想我必须使用" connect by"功能,但我不知道如何使用它。 结果是:
ID Qty
1 1
2 3
3 1
4 1
答案 0 :(得分:1)
CONNECT BY
是必需的。诀窍是省略START WITH
子句,因此每个部门都被视为“根”。然后,我们可以计算每个“根”的员工 - 即每个部门及其所有子部门。
这是你的例子。我还为您的部门结构添加了一个额外的级别,作为一个更高级的测试用例。
WITH dept ( id, name, parent_id) AS (
SELECT 1, 'dep1', null FROM DUAL UNION ALL
SELECT 2, 'dep2', null FROM DUAL UNION ALL
SELECT 3, 'dep21', 2 FROM DUAL UNION ALL
SELECT 4,'dep22', 2 FROM DUAL UNION ALL
SELECT 5, 'dep211', 3 FROM DUAL
),
emp (id, name, dep_id) AS (
SELECT 1, 'Name1', 3 FROM DUAL UNION ALL
SELECT 2, 'Name2', 4 FROM DUAL UNION ALL
SELECT 3, 'Name3', 1 FROM DUAL UNION ALL
SELECT 4, 'Name4', 2 FROM DUAL UNION ALL
SELECT 5, 'Name5', 5 FROM DUAL
),
intermediate as (
select connect_by_root d.name deptname, level lvl, e.id empid, e.name empname
from dept d left join emp e on e.dep_id = d.id
-- Unfortunately, connecting this way, we cannot also determine the "level" of each
-- department. To do that, we would need the CONNECT BY to be reversed, i.e.,:
-- connect by prior d.parent_id = d.id
connect by d.parent_id = prior d.id
-- No "START WITH" clause
)
SELECT deptname,
count(empid) empcount,
listagg(empname,', ') within group ( order by empname) emplist
FROM intermediate
GROUP BY deptname
ORDER BY deptname;
+----------+----------+----------------------------+ | DEPTNAME | EMPCOUNT | EMPLIST | +----------+----------+----------------------------+ | dep1 | 1 | Name3 | | dep2 | 4 | Name1, Name2, Name4, Name5 | | dep21 | 2 | Name1, Name5 | | dep211 | 1 | Name5 | | dep22 | 1 | Name2 | +----------+----------+----------------------------+