Tutorial Intro

PreparedStatements are precompiled SQL statements within the JDBC API. They offer significant advantages over using Statement directly, particularly for applications with frequent SQL execution or when dealing with user input to prevent SQL injection vulnerabilities.

Key Advantages

Performance: PreparedStatements are compiled once by the database server and then reused for subsequent executions. This eliminates the overhead of parsing and compiling the SQL statement repeatedly, leading to significant performance gains. Security: SQL Injection Prevention: By using placeholders (e.g., ?) for input values, PreparedStatements prevent SQL injection attacks. The JDBC driver properly escapes and handles user-supplied input, ensuring that it cannot be manipulated to alter the intended SQL query. Improved Code Structure: PreparedStatements make your code more readable and maintainable by separating the SQL query from the input values. This separation enhances code clarity and makes it easier to modify or debug. Reduced Network Traffic: Since the SQL statement is only sent to the server once for compilation, subsequent executions with different parameter values require only the parameter data to be transmitted, reducing network traffic.

Java PreparedStatement Example import java.sql.*; public class PreparedStatementExample { public static void main(String[] args) { try { // 1. Load the JDBC driver Class.forName("com.mysql.cj.jdbc.Driver"); // 2. Establish a connection Connection connection = DriverManager.getConnection( "jdbc:mysql://localhost:3306/your_database", "your_username", "your_password"); // 3. Create a PreparedStatement String sql = "INSERT INTO users (username, email) VALUES (?, ?)"; PreparedStatement preparedStatement = connection.prepareStatement(sql); // 4. Set parameters preparedStatement.setString(1, "john.doe"); preparedStatement.setString(2, "john.doe@example.com"); // 5. Execute the query int rowsInserted = preparedStatement.executeUpdate(); System.out.println(rowsInserted + " rows inserted."); // 6. Close resources preparedStatement.close(); connection.close(); } catch (ClassNotFoundException | SQLException e) { e.printStackTrace(); } } }

Explanation ⯁ Load the Driver: The Class.forName() method loads the JDBC driver for the specific database you're using (in this case, MySQL). ⯁ Establish Connection: DriverManager.getConnection() establishes a connection to the database using the provided URL, username, and password. ⯁ Create PreparedStatement: connection.prepareStatement() creates a PreparedStatement object with the given SQL query. Note the use of placeholders (?) for the username and email values. ⯁ Set Parameters: preparedStatement.setString(1, "john.doe"); sets the first parameter (index starts from 1) to "john.doe". Similarly, preparedStatement.setString(2, "john.doe@example.com"); sets the second parameter. ⯁ Execute the Query: preparedStatement.executeUpdate() executes the prepared statement and returns the number of rows affected (in this case, the number of rows inserted). ⯁ Close Resources: It's crucial to close the PreparedStatement and the Connection to release database resources. Key Points ⯁ Replace the placeholders with actual values using setString(), setInt(), setDate(), etc., depending on the data type. ⯁ For queries that return results, use preparedStatement.executeQuery() instead of executeUpdate(). ⯁ PreparedStatements are particularly beneficial for parameterized queries, where the same SQL structure is used with varying input values."

Tutorials