JDBC练习_insert语句和update语句和delete

添加一条insert记录

public static void main(String[] args) {
        Statement stmt=null;
        Connection conn =null;
        try {
            //1.注册驱动
            Class.forName("com.mysql.cj.jdbc.Driver");
            //2.定义sql
            String sql = "insert into account values(null,'王五',3000)";
            //3.获取Connection对象
            conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/day?serverTimezone=GMT%2B8", "root", "root");
            //4.获取执行sql的对象 Statement
            stmt = conn.createStatement();
            //5.执行sql
            int count = stmt.executeUpdate(sql);//影响的行数
            //6.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) {
            throw new RuntimeException(e);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }finally {
            //7.释放资源
            if (stmt != null) {
                try {
                    stmt.close();
                } catch (SQLException e) {
                    throw new RuntimeException(e);
                }
            }
            if (conn!=null) {
                try {
                    conn.close();
                } catch (SQLException e) {
                    throw new RuntimeException(e);
                }
            }
        }
    }

update语句修改记录

public static void main(String[] args) {
        Connection conn = null;
        Statement stmt = null;
        try {
            // 1.注册驱动
            Class.forName("com.mysql.jdbc.Driver");
            // 2.获取连接对象
            conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/day?serverTimezone=GMT%2B8", "root", "root");
            // 3.定义sql
            String sql = "update account set balance = 1500 where id=3";
            // 4.获取执行sql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) {
            throw new RuntimeException(e);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        } finally {
            // 7.释放资源
            if (stmt != null){
                try {
                    stmt.close();
                } catch (SQLException e) {
                    throw new RuntimeException(e);
                }
            }
            if (conn != null){
                try {
                    conn.close();
                } catch (SQLException e) {
                    throw new RuntimeException(e);
                }
            }
        }
    }

delete语句删除一条记录

public static void main(String[] args) {
        Connection conn = null;
        Statement stmt = null;
        try {
            // 1.注册驱动
            Class.forName("com.mysql.jdbc.Driver");
            // 2.获取连接对象
            conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/day?serverTimezone=GMT%2B8", "root", "root");
            // 3.定义sql
            String sql = "delete  from account where id=3";
            // 4.获取执行sql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) {
            throw new RuntimeException(e);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        } finally {
            // 7.释放资源
            if (stmt != null){
                try {
                    stmt.close();
                } catch (SQLException e) {
                    throw new RuntimeException(e);
                }
            }
            if (conn != null){
                try {
                    conn.close();
                } catch (SQLException e) {
                    throw new RuntimeException(e);
                }
            }
        }
    }