How Can I Prevent SQL Injection When Using User Input in MySQL's LIMIT Clause?

Avoid SQL Injection by Properly Handling Variables in LIMIT Clause

When querying a database with user-supplied input, ensuring data integrity and preventing SQL injection is crucial. However, when using the bindValue method in MySQL's LIMIT clause, it's critical to handle input values correctly.

In the provided code snippet, the error arises from single quotes being added to the :skip parameter in the LIMIT part of the SQL statement. This discrepancy is caused by PHP's PDO automatically enclosing non-integer values in single quotes.

To resolve this issue, ensure that the :skip parameter is cast as an integer before being passed to the bindValue method:

$fetchPictures->bindValue(':skip', (int) trim($_GET['skip']), PDO::PARAM_INT);

By coercing the value to an integer, we avoid the addition of single quotes, which can lead to SQL injection vulnerabilities. This practice ensures that user-supplied input is properly sanitized before being used in the SQL query.

Remember that casting to an integer only works if the input is a numeric string. For non-numeric input, appropriate validation and error handling mechanisms should be implemented.

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