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Combining MySQL aggregate functions with MySQL IF() function can be very helpful to get the specific output we want. Consider the following queries which combine SUM() and COUNT() aggregate functions with IF() function.

Example

mysql> Select SUM(IF(Language = 'English', 1, 0)) As English, SUM(IF(Language <> 'English',1,0)) AS "Non-English" from Students;
+---------+-------------+
| English | Non-English |
+---------+-------------+
| 5       | 4           |
+---------+-------------+
1 row in set (0.00 sec)

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上述查詢將SUM()聚合函數與IF()函數結合使用，從“學生”表中獲取英語母語學生和非英語母語學生的輸出。

mysql> Select COUNT(IF(country = 'USA', 1, NULL))AS USA,
    -> COUNT(IF(country = 'UK', 1, NULL))AS UK,
    -> COUNT(IF(country = 'France', 1, NULL))AS France,
    -> COUNT(IF(country = 'Russia', 1, NULL))AS Russia,
    -> COUNT(IF(country = 'Australia', 1, NULL))AS Australia,
    -> COUNT(IF(country = 'INDIA', 1, NULL))AS INDIA,
    -> COUNT(IF(country = 'NZ', 1, NULL))AS NZ FROM Students;
+-----+----+--------+--------+-----------+-------+----+
| USA | UK | France | Russia | Australia | INDIA | NZ |
+-----+----+--------+--------+-----------+-------+----+
| 2   | 1  | 1      | 1      | 1         | 2     | 1  |
+-----+----+--------+--------+-----------+-------+----+
1 row in set (0.07 sec)

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上面的查詢將COUNT()聚合函數與IF()函數結合起來，以從“Students”表中獲取國家數量的輸出。

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