JDBC-Connecion详解注册驱动和Statement详解注册驱动

Connecion详解注册驱动

Connection:数据库连接对象

功能：

获取执行sql的对象

Statement createStatement();
PreparedStatement PrepareStatement(String sql)

管理事务

开启事务:setAutoCommit(boolean autocommit):调用该方法设置参数为false 即开启事务
提交事务:Commit();
回滚事务:rollback();

Statement详解注册驱动

statement:执行sql的对象

功能

1.boolean execute(String sql):可以执行任意的sql 
2.int ececuteUpdate(String sql):执行DML(insert、update、delete)语句、DDL(create,alter,drop)语句
返回值:影响的行数 可以通过这个影响的行数判断DML语句是否执行成功 返回值>0的则执行成功 反之 则失败
3.ResultSet executeQuery(String sql):执行DQL（select）语句

练习

1.account表添加一条记录

代码

 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");
            //定义SQL语句
            String sql = "INSERT INTO account values(null,'王五',3000)";
            //获取Connection对象
            conn = DriverManager.getConnection("jdbc:mysql:///videopractice", "root", "root");
            //获取执行SQL的对象 statement
            stmt = conn.createStatement();
            //执行sql
            int count = stmt.executeUpdate(sql);//影响的行数
            //处理结果
            System.out.println(count);
            if (count > 0) {
                System.out.println("添加成功!");
            } else {
                System.out.println("添加失败!");
            }
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        } catch (SQLException throwables) {
            throwables.printStackTrace();
        } finally {
            if (stmt != null) {
                try {
                    stmt.close();
                } catch (SQLException throwables) {
                    throwables.printStackTrace();
                }
            }

            if (conn != null) {
                try {
                    conn.close();

                } catch (SQLException throwables) {
                    throwables.printStackTrace();
                }

            }
        }
    }

运行结果

SQL数据表

2.account表删除一条记录

数据表

代码

 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");
            //定义SQL语句
            String sql = "delete from account where id=4";
            //获取Connection对象
            conn = DriverManager.getConnection("jdbc:mysql:///videopractice", "root", "root");
            //获取执行SQL的对象 statement
            stmt = conn.createStatement();
            //执行sql
            int count = stmt.executeUpdate(sql);//影响的行数
            //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 {
            if (stmt != null) {
                try {
                    stmt.close();
                } catch (SQLException throwables) {
                    throwables.printStackTrace();
                }
            }

            if (conn != null) {
                try {
                    conn.close();

                } catch (SQLException throwables) {
                    throwables.printStackTrace();
                }

            }
        }
    }