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 . "%";

2. Prepare the query using a placeholder:

$ stmt = $ mysqli -> prepare('SELECT * FROM REGISTRY WHERE name LIKE ?');

3. Bind the LIKE variable to the placeholder:

$stmt -> bind_param('s', $likeVar);

4. 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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