Java之简单的jdbc连接MySQL数据库实现增删改查

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JDBC连接数据库执行流程：

1.加载驱动
2.获取连接:与数据库建立连接
3.sql预编译对象:预编译对象
4.执行sql语句
5.释放资源

/**
 * 1.加载mysql驱动：com.mysql.jdbc.Driver 
 * 2.获取连接:与数据库建立连接
 * 3.sql预编译对象:预编译对象
 * 4.执行sql语句
 * 5.释放资源
 * @author 郑清
 */
public class JDBC_CRUD_Demo {

	public static void main(String[] args) {
		testCreateDatabase();//创建数据库
		add();//添加数据
		delete();//删除数据
		update();//修改数据
		select();//查找数据
	}
	
	public static void testCreateDatabase() {
		Connection connection = null;
		Statement statement = null;
		try {
			//1.加载驱动
			Class.forName("com.mysql.jdbc.Driver");
			//2.获取连接：与数据库建立连接
			connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/zhengqing_test", "root", "root");
			//3.获得sql的预编译对象
			statement = connection.createStatement();
			//4.执行sql语句    ex:创建表t_user
			String sql = "CREATE TABLE t_user("
					+" `id` int(11) NOT NULL,"
					+" `username` varchar(20) NOT NULL,"
					+" `password` int(11) NOT NULL,"
					+"  PRIMARY KEY (`id`)"
					+"  ) ENGINE=InnoDB DEFAULT CHARSET=utf8;";
			statement.executeUpdate(sql);
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally {
			//5.释放资源      (注意：关闭资源顺序 先打开后关闭)
			try {
				if(statement!=null) {
					statement.close();
				}
			} catch (SQLException e) {
				e.printStackTrace();
			}finally{
				try {
					if(connection!=null) {
						connection.close();
					}
				} catch (SQLException e) {
					e.printStackTrace();
				}
			}
		}	
	}
	
	public static void add() {
		Connection connection = null;
		Statement statement = null;
		try {
			//1.加载驱动
			Class.forName("com.mysql.jdbc.Driver");
			//2.获取连接：与数据库建立连接
			connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/zhengqing_test", "root", "root");
			//3.获得sql的预编译对象
			statement = connection.createStatement();
			//4.执行sql语句    ex:插入数据到表t_user
			String sql = "insert into t_user(id,username,password) values(2,'张三','123'),(10,'李四','123456');";
			statement.executeUpdate(sql);
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally {
			//5.释放资源      (注意：关闭资源顺序 先打开后关闭)
			try {
				if(statement!=null) {
					statement.close();
				}
			} catch (SQLException e) {
				e.printStackTrace();
			}finally{
				try {
					if(connection!=null) {
						connection.close();
					}
				} catch (SQLException e) {
					e.printStackTrace();
				}
			}
		}
	}

	public static void delete() {
		Connection connection = null;
		Statement statement = null;
		try {
			//1.加载驱动
			Class.forName("com.mysql.jdbc.Driver");
			//2.获取连接：与数据库建立连接
			connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/zhengqing_test", "root", "root");
			//3.获得sql的预编译对象
			statement = connection.createStatement();
			//4.执行sql语句    ex:删除表t_user中的数据
			String sql = "delete from t_user where id = 2;";
			statement.executeUpdate(sql);
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally {
			//5.释放资源      (注意：关闭资源顺序 先打开后关闭)
			try {
				if(statement!=null) {
					statement.close();
				}
			} catch (SQLException e) {
				e.printStackTrace();
			}finally{
				try {
					if(connection!=null) {
						connection.close();
					}
				} catch (SQLException e) {
					e.printStackTrace();
				}
			}
		}
	}
	
	public static void update() {
		Connection connection = null;
		Statement statement = null;
		try {
			//1.加载驱动
			Class.forName("com.mysql.jdbc.Driver");
			//2.获取连接：与数据库建立连接
			connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/zhengqing_test", "root", "root");
			//3.获得sql的预编译对象
			statement = connection.createStatement();
			//4.执行sql语句    ex:修改表t_user中数据
			String sql = "update t_user set username='修改名字',password='111111' where id=3;";
			statement.executeUpdate(sql);
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally {
			//5.释放资源      (注意：关闭资源顺序 先打开后关闭)
			try {
				if(statement!=null) {
					statement.close();
				}
			} catch (SQLException e) {
				e.printStackTrace();
			}finally{
				try {
					if(connection!=null) {
						connection.close();
					}
				} catch (SQLException e) {
					e.printStackTrace();
				}
			}
		}
	}
	
	public static void select() {
		Connection connection = null;
		Statement statement = null;
		ResultSet rs = null;
		try {
			//1.加载驱动
			Class.forName("com.mysql.jdbc.Driver");
			//2.获取连接：与数据库建立连接
			connection = DriverManager.getConnection("jdbc:mysql://localhost:3306/zhengqing_test", "root", "root");
			//3.获得sql的预编译对象
			statement = connection.createStatement();
			//4.执行sql语句    ex:查找表t_user中数据
			//查找id为3的一条数据
			/*String sql = "select * from t_user where id = 3;";
			rs = statement.executeQuery(sql);
			System.out.println(rs.next());
			System.out.println(rs.getInt("id"));
			System.out.println(rs.getString("username"));
			System.out.println(rs.getString("password"));*/
			//查找表中全部数据
			String sql = "select * from t_user;";
			rs = statement.executeQuery(sql);
			while(rs.next()){
				System.out.print(rs.getInt("id")+"-->");
				System.out.print(rs.getString("username")+"-->");
				System.out.println(rs.getString("password"));
			}
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}finally {
			//5.释放资源      (注意：关闭资源顺序 先打开后关闭)
			try {
				if(rs!=null)rs.close();
			} catch (SQLException e) {
				e.printStackTrace();
			}finally{
				try {
					if(statement!=null)statement.close();
				} catch (SQLException e) {
					e.printStackTrace();
				}finally{
					try {
						if(connection!=null)connection.close();
					} catch (SQLException e) {
						e.printStackTrace();
					}
				}
			}
		}
	}
	
}