The INSERT ... ON DUPLICATE KEY UPDATE works in a way that if it finds a duplicate unique or primary key, it will perform an UPDATE. The UPDATE is performed only when duplicate values occur.
Let us first create a table −
mysql> create table DemoTable733 ( StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY, StudentName varchar(100), StudentMarks int, UNIQUE KEY Un_Name (StudentName) ); Query OK, 0 rows affected (0.60 sec)
Insert some records in the table using insert command −
mysql> insert into DemoTable733(StudentName,StudentMarks) values('John',45) ON DUPLICATE KEY UPDATE StudentMarks=86; Query OK, 1 row affected (0.19 sec) mysql> insert into DemoTable733(StudentName,StudentMarks) values('Adam',65) ON DUPLICATE KEY UPDATE StudentMarks=86; Query OK, 1 row affected (0.15 sec) mysql> insert into DemoTable733(StudentName,StudentMarks) values('Carol',75) ON DUPLICATE KEY UPDATE StudentMarks=86; Query OK, 1 row affected (0.08 sec) mysql> insert into DemoTable733(StudentName,StudentMarks) values('John',45) ON DUPLICATE KEY UPDATE StudentMarks=86; Query OK, 2 rows affected (0.12 sec)
Display all records from the table using select statement −
mysql> select *from DemoTable733;
This will produce the following output -
+-----------+-------------+--------------+ | StudentId | StudentName | StudentMarks | +-----------+-------------+--------------+ | 1 | John | 86 | | 2 | Adam | 65 | | 3 | Carol | 75 | +-----------+-------------+--------------+ 3 rows in set (0.00 sec)