ใช้คีย์เวิร์ด DISTINCT ใน SELECT จะกรองแถวที่ซ้ำกันทั้งแถว (ทุกคอลัมน์ที่ SELECT):
ตัวอย่าง
mysql> SELECT * FROM student; +------+---------+---------+-----------+ | Id | Name | Address | Subject | +------+---------+---------+-----------+ | 1 | Gaurav | Delhi | Computers | | 2 | Aarav | Mumbai | History | | 15 | Harshit | Delhi | Commerce | | 17 | Raman | Shimla | Computers | | 20 | Gaurav | Jaipur | History | +------+---------+---------+-----------+ mysql> SELECT DISTINCT Address FROM student; +---------+ | Address | +---------+ | Delhi | | Mumbai | | Shimla | | Jaipur | +---------+ mysql> SELECT DISTINCT * FROM student; -- ไม่มีแถวซ้ำทั้งแถว จึงคืนทั้งหมด +------+---------+---------+-----------+ | Id | Name | Address | Subject | +------+---------+---------+-----------+ | 1 | Gaurav | Delhi | Computers | | 2 | Aarav | Mumbai | History | | 15 | Harshit | Delhi | Commerce | | 17 | Raman | Shimla | Computers | | 20 | Gaurav | Jaipur | History | +------+---------+---------+-----------+ mysql> SELECT DISTINCT Name FROM student; +---------+ | Name | +---------+ | Gaurav | | Aarav | | Harshit | | Raman | +---------+
DISTINCT ใช้กับการรวมคอลัมน์ที่ SELECT ทั้งหมด
