How MySQL aggregate functions can be combined with MySQL IF() function?

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)

The above query combines SUM() aggregate function with IF() function to get the output of English speaking students and non-English speaking students from ‘Students’ table.

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)

The above query combines COUNT() aggregate function with IF() function to get the output of a number of countries from ‘Students’ table.

Moumita

Published on 21-Feb-2018 05:58:27

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