Question

我有两张桌子：

文档表（documentID，userID）和sers表（UserID，FirstName，LastName）。

例如

文件表：

documentID = 1 | userID = 2 | modifiedUser = 2
documentID = 3 | userID = 1 | modifiedUser = 1

用户表：

userID = 1 | firstName = Bob  | lastName = Hope
userID = 2 | firstName = John | lastName = Doe

我需要SQL查询来选择文档表中的所有列，但应该连接用户的名字和姓氏而不是userID

我的输出应该是：

documentID = 1 | userID = John Doe | modifiedUser = John Doe
documentID = 3 | userID = Bob Hope | modifiedUser = Bob Hope

有什么想法吗？

Answer 1

更新：更新了查询以反映问题中的更改：

简单JOIN应该：

SELECT documentID, 
 concat(u.firstName,' ',u.lastName) AS userID,
 concat(mu.firstName,' ',mu.lastName) AS userID 
FROM document
JOIN user u ON (u.userID=document.userID)
JOIN user mu ON (mu.userID=document.modifiedUser);

Answer 2

SELECT d.document_id, u.firstName||u.lastName AS 'user_id'
FROM document d JOIN user u
ON d.userID=u.userID;

这应该有用。

Answer 3

  SELECT d.documentID, concat_ws(' ', u.firstName, u.lastName) AS userID 
    FROM document d, user u 
   WHERE u.userID = d.userID ;

Answer 4

你需要这个：

SELECT A.documentID, 
CONCAT_WS(' ', B.firstName, B.lastName) AS userID 
FROM document  A, USER B 
WHERE B.userID = A.userID 
ORDER BY A.documentID;

输出应该是：

+----------+----------+
|documentID| userID   |
+----------+----------+
|   1      | jhon doe |
+----------+----------+
|   3      | bob hope |
+----------+----------+

更新：1

SELECT A.documentID, 
CONCAT_WS(' ', B.firstName, B.lastName) AS userID, 
CONCAT_WS(' ', B.firstName, B.lastName) AS modifiedUser  
FROM document  A, USER B 
WHERE B.userID = A.userID 
ORDER BY A.documentID;

输出如：

+----------+----------+------------+
|documentID| userID   |modifiedUser|
+----------+----------+------------+
|   1      | jhon doe |  jhon doe  |
+----------+----------+------------+
|   3      | bob hope |  bob hope  |
+----------+----------+------------+

<强> http://dev.mysql.com/doc/refman/5.0/en/string-functions.html#function_concat-ws

Mysql与其他表连接用户表

4 个答案: