Ignore MySQL INSERT IGNORE statement and display an error if duplicate values are inserted in a table

Let us first create a table −

mysql> create table DemoTable
(
   FirstName varchar(100)
);
Query OK, 0 rows affected (0.58 sec)

As stated in the official MySQL docs, “without IGNORE, a row that duplicates an existing UNIQUE index or PRIMARY KEY value in the table causes a duplicate-key error and the statement is aborted”.

Therefore, let us now add a unique index −

mysql> alter table DemoTable add unique index(FirstName);
Query OK, 0 rows affected (0.50 sec)
Records: 0 Duplicates: 0 Warnings: 0

Insert some records in the table using insert command. As you can see, since we haven’t used INSERT IGNORE, an error would be visible while inserting duplicate records −

mysql> insert into DemoTable values('Chris');
Query OK, 1 row affected (0.32 sec)
mysql> insert into DemoTable values('Robert');
Query OK, 1 row affected (0.09 sec)
mysql> insert into DemoTable values('David');
Query OK, 1 row affected (0.15 sec)
mysql> insert into DemoTable values('Robert');
ERROR 1062 (23000): Duplicate entry 'Robert' for key 'FirstName'
mysql> insert into DemoTable values('Chris');
ERROR 1062 (23000): Duplicate entry 'Chris' for key 'FirstName'
mysql> insert into DemoTable values('Sam');
Query OK, 1 row affected (0.12 sec)

Display all records from the table using select statement −

mysql> select *from DemoTable;

This will produce the following output −

+-----------+
| FirstName |
+-----------+
| Chris     |
| David     |
| Robert    |
| Sam       |
+-----------+
4 rows in set (0.00 sec)

AmitDiwan

Published on 24-Sep-2019 16:40:58