JDBC练习_update语句和DDL语句

JDBC练习_update语句

account表 修改记录：

 

/**
 * account表 修改记录
 */
public class JDBCDemo03 {
    public static void main(String[] args) {
        Connection conn = null;
        Statement stmt = null;
        try {
            //1.注册驱动
            Class.forName("com.mysql.cj.jdbc.Driver");
            //2.获取连接对象
            conn = DriverManager.getConnection("jdbc:mysql:///db1", "root", "root");
            //3.定义sql
            String sql = "update account set balance = 1500 where id = 3";
            //4.获取执行sql的对象
            stmt = conn.createStatement();
            //5.执行sql
            int count = stmt.executeUpdate(sql);
            //6.处理结果
            System.out.println(count);
            if (count>0){
                System.out.println("修改成功");
            }else {
                System.out.println("修改失败");
            }
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }finally {
            //7.释放资源
            if (stmt!=null){
                try {
                    stmt.close();
                } catch (SQLException throwables) {
                    throwables.printStackTrace();
                }
            }
            if (conn!=null){
                try {
                    conn.close();
                } catch (SQLException throwables) {
                    throwables.printStackTrace();
                }
            }
        }
    }
}

 

 

 

 

 

 

 

 

 

 

 

 

JDBC练习_delete、DDL语句

删除account表中的记录：

/**
 * account表 删除一条记录
 */
public class JDBCDemo04 {
    public static void main(String[] args) {
        Connection conn = null;
        Statement stmt = null;
        try {
            //1.注册驱动
            Class.forName("com.mysql.cj.jdbc.Driver");
            //2.获取连接对象
            conn = DriverManager.getConnection("jdbc:mysql:///db1", "root", "root");
            //3.定义sql
            String sql = "delete from account where id = 3";
            //4.获取执行sql的对象
            stmt = conn.createStatement();
            //5.执行sql
            int count = stmt.executeUpdate(sql);
            //6.处理结果
            System.out.println(count);
            if (count>0){
                System.out.println("删除成功");
            }else {
                System.out.println("删除失败");
            }
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }finally {
            //7.释放资源
            if (stmt!=null){
                try {
                    stmt.close();
                } catch (SQLException throwables) {
                    throwables.printStackTrace();
                }
            }
            if (conn!=null){
                try {
                    conn.close();
                } catch (SQLException throwables) {
                    throwables.printStackTrace();
                }
            }
        }
    }
}

 

执行DDL语句：

/**
 * 执行DDL语句
 */
public class JDBCDemo05 {
    public static void main(String[] args) {
        Connection conn = null;
        Statement stmt = null;
        try {
            //1.注册驱动
            Class.forName("com.mysql.cj.jdbc.Driver");
            //2.获取连接对象
            conn = DriverManager.getConnection("jdbc:mysql:///db1", "root", "root");
            //3.定义sql
            String sql = "create table acc1(id int,name varchar(20))";
            //4.获取执行sql的对象
            stmt = conn.createStatement();
            //5.执行sql
            int count = stmt.executeUpdate(sql);
            //6.处理结果
            System.out.println(count);
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        }finally {
            //7.释放资源
            if (stmt!=null){
                try {
                    stmt.close();
                } catch (SQLException throwables) {
                    throwables.printStackTrace();
                }
            }
            if (conn!=null){
                try {
                    conn.close();
                } catch (SQLException throwables) {
                    throwables.printStackTrace();
                }
            }
        }
    }
}