Passing Parameters to a JDBC PreparedStatement

Creating a validation class for a Java program often involves querying a database. The following code attempts to select a specific row from a table using a PreparedStatement with a parameter:

public class Validation {

    // ...

    public Validation(String userID) {
        try {
            // ...
            statement = con.prepareStatement(
                    "SELECT * from employee WHERE  userID = "   "''"   userID);
            // ...
        } catch (Exception ex) {
            // ...
        }
    }

    // ...
}

However, this code may not work because the SQL statement is not formatted correctly.

Solution:

To correctly pass a parameter to a PreparedStatement, use the setString() method:

statement = con.prepareStatement("SELECT * from employee WHERE  userID = ?");
statement.setString(1, userID);

This method sets the value of the first parameter (?) to the specified user ID. It ensures that the statement is formatted properly and prevents SQL injection, a security vulnerability that occurs when malicious SQL code is injected into a query.

For more information on using PreparedStatements, refer to the Java Tutorials.