In Java, a PreparedStatement is a feature of the JDBC API that allows you to execute parameterized SQL statements. A PreparedStatement is a precompiled SQL statement that can be executed multiple times with different parameters, which makes it more efficient than creating a new Statement object for each execution.
To use a PreparedStatement, you first create an instance of it by calling the prepareStatement() method on a Connection object. Here’s an example:
String sql = "SELECT * FROM my_table WHERE id = ?"; PreparedStatement statement = connection.prepareStatement(sql);
In this example, we’re preparing a SQL SELECT statement that retrieves data from a table called “my_table” based on an ID parameter. The “?” symbol is a placeholder for the parameter.
Once you have created the PreparedStatement object, you can set the parameter values by calling the appropriate set methods on the PreparedStatement object, passing in the index of the parameter and the value. Here’s an example:
In this example, we’re setting the value of the first parameter to 123.
Finally, you can execute the PreparedStatement object by calling the executeQuery() method on it, which returns a ResultSet object containing the results of the query. Here’s an example:
ResultSet resultSet = statement.executeQuery();
In this example, we’re executing the PreparedStatement object and storing the results in a ResultSet object.
Here’s another example of how you can use a PreparedStatement in Java to update data in a database:
String sql = "UPDATE my_table SET name = ?, age = ? WHERE id = ?"; PreparedStatement statement = connection.prepareStatement(sql); statement.setString(1, "John Doe"); statement.setInt(2, 35); statement.setInt(3, 123); int rowsUpdated = statement.executeUpdate();
In this example, we’re preparing a SQL UPDATE statement that updates the “name” and “age” columns in a table called “my_table” based on an ID parameter. We then set the values of the parameters using the setString() and setInt() methods on the PreparedStatement object.
Finally, we execute the PreparedStatement object by calling the executeUpdate() method, which returns the number of rows that were updated. In this example, we’re storing the result in an integer variable called “rowsUpdated”.
Using a PreparedStatement in Java provides several benefits, including improved performance and security. By precompiling the SQL statement and parameterizing it, you can reuse the statement multiple times with different parameters, which reduces the overhead of parsing and compiling the statement. Additionally, using parameterized SQL statements can help prevent SQL injection attacks by separating the SQL code from the user input.