ignore-duplicates-when-inserting-records.md

Ignore Duplicates When Inserting Records

While trying to run a seed script to set up some application data in a MySQL database, I ran into several duplicate-key errors. Some of this data had already been added in another context, but I still need some of the seeds.

insert into MerchantAccount (col1, col2, col3)
  values ('data1', 'data2', 'data3'),
         ('data4', 'data5', 'data6'),
         (...);

The solution was to allow MySQL to ignore the duplicate records and insert the rest.

insert ignore into MerchantAccount (col1, col2, col3)
  values ('data1', 'data2', 'data3'),
         ('data4', 'data5', 'data6'),
         (...);

Notice all I had to do was update the statment by adding ignore right after insert.

If you use the IGNORE modifier, ignorable errors that occur while executing the INSERT statement are ignored. For example, 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. With IGNORE, the row is discarded and no error occurs. Ignored errors generate warnings instead.

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