完全加入Mysql失敗

Question

我想學習加入。但是，當我嘗試完全加入員工和工資表時，它失敗了。爲什麼失敗？

我已添加解決方案的結果，僅供參考。

mysql> select * from employee; 
+-----+---------+ 
| eid | ename | 
+-----+---------+ 
| 1 | sampath | 
| 2 | maclean | 
| 3 | sudheer | 
+-----+---------+ 
3 rows in set (0.00 sec) 

mysql> select * from Salary; 
+------+--------+------+ 
| sid | salary | eid | 
+------+--------+------+ 
| 1001 | 5000 | 2 | 
| 1002 | 70000 | 3 | 
| 1003 | 70000 | 3 | 
+------+--------+------+ 
3 rows in set (0.00 sec) 

mysql> select employee.eid, employee.ename, Salary.salary from employee JOIN Salary on employee.eid=Salary.eid; 
+-----+---------+--------+ 
| eid | ename | salary | 
+-----+---------+--------+ 
| 2 | maclean | 5000 | 
| 3 | sudheer | 70000 | 
| 3 | sudheer | 70000 | 
+-----+---------+--------+ 
3 rows in set (0.00 sec) 

mysql> select employee.eid, employee.ename, Salary.salary from employee LEFT JOIN Salary ON employee.eid=Salary.eid; 
+-----+---------+--------+ 
| eid | ename | salary | 
+-----+---------+--------+ 
| 1 | sampath | NULL | 
| 2 | maclean | 5000 | 
| 3 | sudheer | 70000 | 
| 3 | sudheer | 70000 | 
+-----+---------+--------+ 
4 rows in set (0.00 sec) 

mysql> select employee.eid, employee.ename, Salary.salary from employee RIGHT JOIN Salary ON employee.eid=Salary.eid; 
+------+---------+--------+ 
| eid | ename | salary | 
+------+---------+--------+ 
| 2 | maclean | 5000 | 
| 3 | sudheer | 70000 | 
| 3 | sudheer | 70000 | 
+------+---------+--------+ 
3 rows in set (0.00 sec) 

的MySQL>選擇employee.eid，employee.ename，Salary.salary從僱員FULL JOIN薪水employee.eid = Salary.eid; ERROR 1054（42S22）：在 '字段列表' 的mysql>

更新未知列 'employee.eid'：以下是左派的結果加入聯盟右鍵加入

mysql> SELECT * FROM employee e 
    -> LEFT JOIN Salary s ON e.eid = s.eid 
    -> UNION 
    -> SELECT * FROM employee e 
    -> RIGHT JOIN Salary s ON e.eid = s.eid; 
+------+---------+------+--------+------+ 
| eid | ename | sid | salary | eid | 
+------+---------+------+--------+------+ 
| 1 | Rai  | NULL | NULL | NULL | 
| 2 | pinto | 1001 | 50000 | 2 | 
| 3 | sudheer | 1002 | 70000 | 3 | 
| 3 | sudheer | 1003 | 70000 | 3 | 
+------+---------+------+--------+------+ 
4 rows in set (0.00 sec) 

Answer 1

MySQL不支持FULL OUTER JOIN關鍵字。只支持LEFT JOIN和RIGHT JOIN。

你可以試試這個模仿相同：

SELECT * FROM employee e 
LEFT JOIN salary s ON e.eid = s.eid 
UNION 
SELECT * FROM employee e 
RIGHT JOIN salary s ON e.eid = s.eid 

Answer 2

MySQL不支持完全加入。

檢查以下問題，希望它會幫助你解決你的問題:)

MySQL FULL JOIN not working but RIGHT and LEFT join works