Question

我想要加入四个表来获取具有相同目录和类型的emp计数如下：

first_char   dir
-------------------
0000         Dir0
1111         Dir1
2222         Dir2

EMP_TYPE

type
------
typeA
typeB
typeC

assigned_num

no      emp_id
-------------------------
1111A   1
1111B   2
0000A   3
1111C   4
2222A   5
2222B   6
0000B   7

EMP

id      type
--------------------
1       typeA
2       typeB
3       typeA
4       typeA
5       typeA    
6       typeB
7       typeA

预期输出

dir    type    # of emp
------------------------
Dir0   typeA   2          --> emp_id 3 and 7    
Dir0   typeB   0
Dir0   typeC   0
Dir1   typeA   2          --> emp_id 1 and 4
Dir1   typeB   1          --> emp_id 2
Dir1   typeC   0
Dir2   typeA   1          --> emp_id 5
Dir2   typeB   1          --> emp_id 6
Dir2   typeC   0

我试过了：

SELECT dire.dir, etype.type, COUNT(anum.emp_id)
FROM emp_type etype
JOIN emp empl
ON etype.type = empl.type 
JOIN assigned_num anum 
ON empl.id = anum.emp_id
JOIN directory dire
ON anum.no LIKE dire.first_char  || '%'
GROUP BY dire.dir, etype.type;

但它不会显示具有0 emp计数的目录和类型

Answer 1

解决你的问题：

SELECT dir.dir, et.type,COUNT(emp.id) No_Of_Emp
FROM emp_Type et
CROSS JOIN Directory dir
LEFT JOIN assigned_num an
ON an.no LIKE dir.first_char  || '%' 
LEFT JOIN emp
ON et.type = emp.type
AND an.emp_id = emp.id
GROUP BY dir.dir, et.type
ORDER BY dir.dir, et.type

<强>输出：

DIR      TYPE   NO_OF_EMP
=========================
Dir0    typeA    2
Dir0    typeB    0
Dir0    typeC    0
Dir1    typeA    2
Dir1    typeB    1
Dir1    typeC    0
Dir2    typeA    1
Dir2    typeB    1
Dir2    typeC    0

点击演示链接：

http://sqlfiddle.com/#!4/e2dd9/59

oracle sql one是很多加入的

1 个答案: