How to prevent duplicate data from being inserted into a MySQL database?

To prevent duplicate data from being inserted into a MySQL database when inserting data via SSH, you can use one or more of the following methods, depending on your specific use case and requirements:

1. Use the INSERT IGNORE Statement:

You can use the INSERT IGNORE statement when inserting data into your MySQL database. This statement will attempt to insert the data, but if a duplicate key violation occurs (e.g., a unique constraint is violated), it will ignore the duplicate and continue with the next row. Here's an example:

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INSERT IGNORE INTO your_table (column1, column2, column3) VALUES (value1, value2, value3);
2. Use the INSERT ON DUPLICATE KEY UPDATE Statement:

If you want to update the existing record when a duplicate key is encountered, you can use the INSERT ON DUPLICATE KEY UPDATE statement. This statement will insert the data, and if a duplicate key violation occurs, it will update the existing record instead. Here's an example:

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INSERT INTO your_table (column1, column2, column3) VALUES (value1, value2, value3)
ON DUPLICATE KEY UPDATE column1 = value1, column2 = value2;
Make sure that you have defined appropriate unique constraints or primary keys on your table columns to identify duplicates.

3. Use INSERT IGNORE with INSERT INTO ... SELECT:

If you are inserting data from one table into another and want to ignore duplicates, you can combine the INSERT IGNORE statement with the INSERT INTO ... SELECT syntax. For example:

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INSERT IGNORE INTO your_table (column1, column2, column3)
SELECT source_column1, source_column2, source_column3 FROM source_table;
This will insert data from source_table into your_table, ignoring duplicates.

4. Use INSERT IGNORE with INSERT INTO ... VALUES for Batch Insertion:

If you are inserting multiple rows at once, you can use the INSERT IGNORE statement with INSERT INTO ... VALUES for batch insertion. For example:

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INSERT IGNORE INTO your_table (column1, column2, column3)
VALUES (value1, value2, value3),
(value4, value5, value6),
(value7, value8, value9);
This will insert multiple rows into your_table, and any duplicates will be ignored.

Choose the method that best suits your needs based on whether you want to simply ignore duplicates, update existing records, or perform batch insertion. Also, ensure that your table has the appropriate unique constraints or primary keys defined to identify duplicate data.