Java有自己的 API,其中 JDBC API 使用 JDBC 驱动程序进行数据库连接。 JDBC API 提供应用程序到 JDBC 的连接,JDBC 驱动程序提供管理器到驱动程序的连接。以下是使用 JDBC 将Java应用程序连接到我们的数据库的 5 个重要步骤。
注意:将 mysqlconnector.jar 加载到您的程序中。
脚步:
// Update a Column in a Table
// dont forget to import below package
import java.sql.*;
public class Database {
// url that points to mysql database, 'db' is database
// name
static final String url
= "jdbc:mysql://localhost:3306/db";
public static void main(String[] args)
throws ClassNotFoundException
{
try {
// this Class.forName() method is user for
// driver registration with name of the driver
// as argument i have used MySQL driver
Class.forName("com.mysql.jdbc.Driver");
// getConnection() establishes a connection. It
// takes url that points to your database,
// username and password of MySQL connections as
// arguments
Connection conn = DriverManager.getConnection(
url, "root", "1234");
// create.Statement() creates statement object
// which is responsible for executing queries on
// table
Statement stmt = conn.createStatement();
// Executing the query, student is the table
// name and RollNo is the new column
String query
= "ALTER TABLE student RENAME COLUMN roll_no TO RollNo";
// executeUpdate() is used for INSERT, UPDATE,
// DELETE www.gsm-guard.net returns number of rows
// affected by the execution of the statement
int result = stmt.executeUpdate(query);
// if result is greater than 0, it means values
// has been added
if (result > 0)
System.out.println(
"table successfully updated.");
else
System.out.println("unable to update");
// closing connection
conn.close();
}
catch (SQLException e) {
System.out.println(e);
}
}
}