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)
上述查询将SUM()聚合函数与IF()函数结合使用，从“学生”表中获取英语母语学生和非英语母语学生的输出。
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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上面的查询将COUNT()聚合函数与IF()函数结合起来，以从“Students”表中获取国家数量的输出。
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