- A PreparedStatement is a feature commonly used in database programming to execute parameterized SQL queries. It is part of the Java Database Connectivity (JDBC) API and is used in Java applications to interact with relational databases like MySQL, Oracle, PostgreSQL, and others.
- PreparedStatement provides a way to execute SQL queries with placeholders for parameters, which helps improve security, performance, and code maintainability.
Preparation:
- First, you create a PreparedStatement object by preparing a SQL statement with placeholders for parameters. These placeholders are typically represented by question marks (?) or named parameters.
Parameterization:
- You set values for the placeholders in the prepared statement using setter methods (e.g., setString, setInt, setDate, etc.) for each parameter. These values can come from user input or other data sources.
- We can execute parameterized query using Spring JdbcTemplate by the help of execute() method of JdbcTemplate class. To use parameterized query, we pass the instance of PreparedStatementCallback in the execute method.
Execution:
- Once the prepared statement is parameterized, you can execute it against the database using the executeQuery method for SELECT statements or executeUpdate for INSERT, UPDATE, DELETE, and other non-query statements.
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
public class PreparedStatementExample {
public static void mai
(String[] args) {
try (Connection connection =
DriverManager.getConnection
("jdbc:mysql:
//localhost:3306/mydb", "username",
"password")) {
String sql = "SELECT *
FROM users WHERE username = ?";
// Create a PreparedStatement
PreparedStatement preparedStatement =
connection.prepareStatement(sql);
// Set the parameter value
preparedStatement.setString(1, "john_doe");
// Execute the query
ResultSet resultSet =
preparedStatement.executeQuery();
// Process the results
while (resultSet.next()) {
System.out.println("User ID: "
+ resultSet.getInt("id"));
System.out.println("Username: "
+ resultSet.getString("username"));
// Add more fields as needed
}
// Close resources
resultSet.close();
preparedStatement.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
- Using PreparedStatement is advantageous because it helps prevent SQL injection attacks, improves query execution performance through query plan caching, and promotes cleaner code by separating SQL logic from data values. It’s considered a best practice for interacting with databases in Java applications.
