IF() ใน SELECT Clause
เงื่อนไขอ้างอิงคอลัมน์ของแถวปัจจุบัน
ข้อมูล Students
+----+-----------+-----------+----------+----------------+
| id | Name | Country | Language | Course |
+----+-----------+-----------+----------+----------------+
| 1 | Francis | UK | English | Literature |
| 2 | Rick | USA | English | History |
| 3 | Correy | USA | English | Computers |
| 4 | Shane | France | French | Computers |
| 5 | Validimir | Russia | Russian | Computers |
| 6 | Steve | Australia | English | Geoinformatics |
| 7 | Rahul | India | Hindi | Yoga |
| 8 | Harshit | India | Hindi | Computers |
+----+-----------+-----------+----------+----------------+
คำสั่ง: แสดง Name, ภาษา (Eng/Other), Course
mysql> SELECT Name,
IF(Language = 'English', 'Eng_Language', 'Other Language') AS 'Native Language',
Course
FROM students;
ผลลัพธ์
+-----------+-----------------+----------------+
| Name | Native Language | Course |
+-----------+-----------------+----------------+
| Francis | Eng_Language | Literature |
| Rick | Eng_Language | History |
| Correy | Eng_Language | Computers |
| Shane | Other Language | Computers |
| Validimir | Other Language | Computers |
| Steve | Eng_Language | Geoinformatics |
| Rahul | Other Language | Yoga |
| Harshit | Other Language | Computers |
+-----------+-----------------+----------------+
หลักการ
- IF 評估 每行的 Language column
- True → 'Eng_Language', False → 'Other Language'
- เหมาะสำหรับ Conditional formatting ใน Report
