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Inserting Records into MySQL: Handling Duplicate Entries

When inserting records into a MySQL database, you may encounter duplicates due to unique field constraints. To handle these situations gracefully, you have several options:

1. INSERT... IGNORE:

If you want to ignore duplicate entries without any error, use the INSERT... IGNORE syntax. This tells MySQL to skip inserting the duplicate record and continue to the next.

2. REPLACE INTO:

This syntax overwrites the old record with the new one having the same key. If you want to replace duplicate entries, use REPLACE INTO.

3. INSERT... ON DUPLICATE KEY UPDATE:

When encountering a duplicate, this syntax allows you to update the record instead of inserting it. Specify the columns and values you want to update within the UPDATE clause.

Examples:

Consider a table tbl with columns id and value. Initially, it has one row: id=1, value=1.

• REPLACE INTO tbl VALUES(1,50); → Results in a single record: id=1, value=50.
• INSERT IGNORE INTO tbl VALUES (1,10); → Ignored, no record inserted.
• INSERT INTO tbl VALUES (1,200) ON DUPLICATE KEY UPDATE value=200; → Results in a single record: id=1, value=200.

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