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How to insert only those records that does not exist in a MySQL table?
To insert when a record does not exist, set the column as UNIQUE INDEX. Let us first create a table −
mysql> create table DemoTable ( Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, FirstName varchar(20) ); Query OK, 0 rows affected (0.30 sec)
Following is the query to create unique index to insert record which does not exist in the ‘FirstName’ column −
mysql> CREATE UNIQUE INDEX index_on_FirstName ON DemoTable(FirstName); Query OK, 0 rows affected (0.56 sec) Records: 0 Duplicates: 0 Warnings: 0
Insert some records in the table using insert command. Now here you can check the insert command inserts only those record which does not exist −
mysql> insert into DemoTable(FirstName) values('Chris');
Query OK, 1 row affected (0.07 sec)
mysql> insert into DemoTable(FirstName) values('Chris');
ERROR 1062 (23000): Duplicate entry 'Chris' for key 'index_on_FirstName'
mysql>
mysql> insert into DemoTable(FirstName) values('Robert');
Query OK, 1 row affected (0.04 sec)
mysql> insert into DemoTable(FirstName) values('Mike');
Query OK, 1 row affected (0.04 sec)
mysql> insert into DemoTable(FirstName) values('Robert');
ERROR 1062 (23000): Duplicate entry 'Robert' for key 'index_on_FirstName'
mysql>Display all records from the table using select statement −
mysql> select *from DemoTable;
This will produce the following output −
+----+-----------+ | Id | FirstName | +----+-----------+ | 1 | Chris | | 2 | Robert | | 3 | Mike | +----+-----------+ 3 rows in set (0.00 sec)
Updated on: 30-Jul-2019
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