Can MySQL Insert Rows Without Errors When Unique Key Conflicts Occur?

Inserting Rows Without Duplication: Understanding "INSERT ... ON DUPLICATE KEY (do nothing)"

Question:

Can MySQL perform an insertion operation without generating an error when a unique key conflict occurs?

Specifically, is there a way to use the INSERT statement to insert a row into a table only if the primary key doesn't already exist?

Answer:

MySQL provides two methods to handle duplicate key conflicts during an INSERT operation:

1. INSERT ... ON DUPLICATE KEY UPDATE

This syntax allows you to specify an additional action to be taken if the insertion operation would result in a duplicate key violation. For example, you could update an existing row with the values from the new row.

However, there is no specific "DO NOTHING" option with the ON DUPLICATE KEY UPDATE clause.

2. INSERT ... ON DUPLICATE KEY UPDATE>

As an alternative, you can use this syntax to essentially ignore the duplicate key conflict. In this case, the id column is assigned to itself, which doesn't trigger any updates.

3. INSERT IGNORE

If you don't require strict error handling and are not concerned about potential issues with auto-increment fields or foreign key constraints, you can use the INSERT IGNORE statement. This syntax skips the insertion operation if a duplicate key is encountered.

Example:

Consider the user_permanent_gift table mentioned in the question. To insert a row into this table without generating an error in case of duplicate keys, you can use the following statement:

INSERT IGNORE INTO user_permanent_gift (fb_user_id, gift_id, purchase_timestamp) VALUES (123, 456, '2022-03-15 12:00:00');

This statement will attempt to insert the row, but if the combination of fb_user_id and gift_id already exists in the table, the insertion will be skipped without generating an error.

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