sql parameters

SQL parameters are values that are used in SQL statements to filter, sort, or update data in a database. They are placeholders that are replaced with actual values at runtime, which helps to prevent SQL injection attacks and improve performance.

In SQL, parameters are typically defined using a question mark (?) or a named parameter syntax. For example, in a prepared statement, you might define a parameter like this:

SELECT * FROM customers WHERE last_name = ?

When you execute the statement, you would provide the actual value for the parameter, like this:

PreparedStatement stmt = conn.prepareStatement(query);
stmt.setString(1, "Smith");
ResultSet rs = stmt.executeQuery();

In this example, the parameter is a string value that is used to filter the results by last name. By using a parameter instead of embedding the value directly in the SQL statement, you can avoid SQL injection attacks and improve performance by allowing the database to optimize the query execution plan.