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Display an error while inserting duplicate records in a MySQL table
For this, you can use UNIQUE KEY. Let us first create a table −
mysql> create table DemoTable1553 -> ( -> EmployeeId int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> EmployeeName varchar(20), -> EmployeeSalary int -> ); Query OK, 0 rows affected (0.47 sec)
Here is the query to add unique key −
mysql> alter table DemoTable1553 add unique(EmployeeSalary); Query OK, 0 rows affected (0.53 sec) Records: 0 Duplicates: 0 Warnings: 0
Insert some records in the table using insert command −
mysql> insert into DemoTable1553(EmployeeName,EmployeeSalary) values('Chris',45000);
Query OK, 1 row affected (0.21 sec)
mysql> insert into DemoTable1553(EmployeeName,EmployeeSalary) values('David',35000);
Query OK, 1 row affected (0.14 sec)
mysql> insert into DemoTable1553(EmployeeName,EmployeeSalary) values('Sam',25000);
Query OK, 1 row affected (0.15 sec)
mysql> insert into DemoTable1553(EmployeeName,EmployeeSalary) values('Carol',45000);
ERROR 1062 (23000): Duplicate entry '45000' for key 'EmployeeSalary'Display all records from the table using select statement −
mysql> select * from DemoTable1553;
This will produce the following output −
+------------+--------------+----------------+ | EmployeeId | EmployeeName | EmployeeSalary | +------------+--------------+----------------+ | 1 | Chris | 45000 | | 2 | David | 35000 | | 3 | Sam | 25000 | +------------+--------------+----------------+ 3 rows in set (0.00 sec)
Updated on: 12-Dec-2019
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