Có SELECT với IF/ELSE trong MySQL không?

Có, SELECT với IF/ELSE hoàn toàn khả thi trong MySQL.

Tạo bảng:

mysql> CREATE TABLE DemoTable721 ( Id INT NOT NULL AUTO_INCREMENT PRIMARY KEY, FirstName VARCHAR(100), Marks INT, CountryName VARCHAR(100) ); Query OK, 0 rows affected (0.57 sec)

Chèn bản ghi:

mysql> INSERT INTO DemoTable721(FirstName,Marks,CountryName) VALUES('Chris',56,'US'); Query OK, 1 row affected (0.14 sec) mysql> INSERT INTO DemoTable721(FirstName,Marks,CountryName) VALUES('Robert',78,'UK'); Query OK, 1 row affected (0.13 sec) mysql> INSERT INTO DemoTable721(FirstName,Marks,CountryName) VALUES('Mike',45,'AUS'); Query OK, 1 row affected (0.16 sec) mysql> INSERT INTO DemoTable721(FirstName,Marks,CountryName) VALUES('Carol',89,'ENG'); Query OK, 1 row affected (0.22 sec)

Hiển thị:

mysql> SELECT * FROM DemoTable721;

Kết quả:

+----+-----------+-------+-------------+ | Id | FirstName | Marks | CountryName | +----+-----------+-------+-------------+ | 1  | Chris     | 56    | US          | | 2  | Robert    | 78    | UK          | | 3  | Mike      | 45    | AUS         | | 4  | Carol     | 89    | ENG         | +----+-----------+-------+-------------+ 4 rows in set (0.00 sec)

Truy vấn SELECT với IF/ELSE:

mysql> SELECT FirstName, IF(Marks > 75, Marks, CountryName) FROM DemoTable721;

Kết quả:

+-----------+----------------------------------+ | FirstName | IF(Marks > 75, Marks, CountryName) | +-----------+----------------------------------+ | Chris     | US                               | | Robert    | 78                               | | Mike      | AUS                              | | Carol     | 89                               | +-----------+----------------------------------+ 4 rows in set (0.00 sec)