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How Can I Safely Use LIKE '%{Var}%' with Prepared Statements in SQL?

Susan Sarandon
Susan SarandonOriginal
2024-12-15 12:02:11545browse

How Can I Safely Use LIKE '%{Var}%' with Prepared Statements in SQL?

Utilizing Prepared Statements with LIKE '%{Var}%' Effectively

When working with sanitized user input in SQL queries, it is recommended to employ prepared statements to mitigate the risk of SQL injection attacks. However, using the LIKE '%{Var}%' pattern with prepared statements can present challenges.

Incorrect Approach:

The following syntax will generate errors:

$sql = 'SELECT * FROM `users` WHERE username LIKE \'%{?}%\' ';
$sql = 'SELECT * FROM `users` WHERE username LIKE %{?}% ';

Correct Approach:

To use LIKE '%{Var}%' with prepared statements correctly, follow these steps:

  1. Create a string variable to hold the LIKE pattern:
$likeVar = "%" . $ yourParam . "%";
  1. Prepare the query using a placeholder:
$ stmt = $ mysqli -> prepare('SELECT * FROM REGISTRY WHERE name LIKE ?');
  1. Bind the LIKE variable to the placeholder:
$stmt -> bind_param('s', $likeVar);
  1. Execute the query:
$stmt -> execute();

Explanation:

  • $likeVar: This variable contains the LIKE pattern with the user-provided parameter prefixed and suffixed with wildcards.
  • prepare() vs. query(): prepare() creates a statement object that can be executed multiple times with different parameters, whereas query() executes a query directly.
  • bind_param(): This method associates the prepared statement parameters with their respective variable values. In this case, the placeholder (?) is bound to $likeVar.
  • execute(): Once the parameters are bound, execute() executes the query with the specified parameters.

By following these steps, you can safely use LIKE '%{Var}%' in your SQL queries while upholding security best practices.

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