SQL FULL OUTER JOIN 關(guān)鍵字

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SQL FULL OUTER JOIN 關(guān)鍵字

FULL OUTER JOIN 關(guān)鍵字只要左表（table1）和右表（table2）其中一個表中存在匹配，則返回行.

FULL OUTER JOIN 關(guān)鍵字結(jié)合了 LEFT JOIN 和 RIGHT JOIN 的結(jié)果。

SQL FULL OUTER JOIN 語法

SELECT
column_name(s)

FROM
table1

FULL OUTER JOIN
table2

ON
table1.column_name=
table2.column_name;

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演示數(shù)據(jù)庫

在本教程中，我們將使用 RUNOOB 樣本數(shù)據(jù)庫。

下面是選自 "Websites" 表的數(shù)據(jù)：

+----+--------------+---------------------------+-------+---------+
| id | name         | url                       | alexa | country |
+----+--------------+---------------------------+-------+---------+
| 1  | Google       | https://www.google.cm/    | 1     | USA     |
| 2  | 淘寶          | https://www.taobao.com/   | 13    | CN      |
| 3  | 菜鳥教程      | http://www.runoob.com/    | 4689  | CN      |
| 4  | 微博          | http://weibo.com/         | 20    | CN      |
| 5  | Facebook     | https://www.facebook.com/ | 3     | USA     |
| 7  | stackoverflow | http://stackoverflow.com/ |   0 | IND     |
+----+---------------+---------------------------+-------+---------+

下面是 "access_log" 網(wǎng)站訪問記錄表的數(shù)據(jù)：

+-----+---------+-------+------------+
| aid | site_id | count | date       |
+-----+---------+-------+------------+
|   1 |       1 |    45 | 2016-05-10 |
|   2 |       3 |   100 | 2016-05-13 |
|   3 |       1 |   230 | 2016-05-14 |
|   4 |       2 |    10 | 2016-05-14 |
|   5 |       5 |   205 | 2016-05-14 |
|   6 |       4 |    13 | 2016-05-15 |
|   7 |       3 |   220 | 2016-05-15 |
|   8 |       5 |   545 | 2016-05-16 |
|   9 |       3 |   201 | 2016-05-17 |
+-----+---------+-------+------------+
9 rows in set (0.00 sec)

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SQL FULL OUTER JOIN 實例

下面的 SQL 語句選取所有網(wǎng)站訪問記錄。

MySQL中不支持 FULL OUTER JOIN，你可以在 SQL Server 測試以下實例。

實例

SELECT Websites.name, access_log.count, access_log.date

FROM Websites

FULL OUTER JOIN access_log

ON Websites.id=access_log.site_id

ORDER BY access_log.count DESC;

注釋：FULL OUTER JOIN 關(guān)鍵字返回左表（Websites）和右表（access_log）中所有的行。如果 "Websites" 表中的行在 "access_log" 中沒有匹配或者 "access_log" 表中的行在 "Websites" 表中沒有匹配，也會列出這些行。

本文題目：創(chuàng)新互聯(lián)MSSQL教程SQL FULL OUTER JOIN 關(guān)鍵字
轉(zhuǎn)載來源：http://m.5511xx.com/article/copjdip.html