JDBC练习_update and DDL语句
//删除数据库内容语句 //导入jar包 public static void main(String[] args) { Connection conn=null; Statement stmt =null; try { //注册驱动 Class.forName("com.mysql.jdbc.Driver"); //获取数据库的连接对象 conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/guo01?useUnicode=true&characterEncoding=utf-8&useSSL=false", "root", "root"); //定义sql语句 String sql = "delete from account where id=3"; //获取执行sql的对象Statement stmt = conn.createStatement(); //获取执行sql int count = stmt.executeUpdate(sql); //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 e) { e.printStackTrace(); }finally { //释放资源 if (stmt !=null){ try { stmt.close(); } catch (SQLException e) { e.printStackTrace(); } } if (conn !=null){ try { conn.close(); } catch (SQLException e) { e.printStackTrace(); } } } } }
DDL语句练习
//执行DDL语句 //导入jar包 public static void main(String[] args) { Connection conn=null; Statement stmt =null; try { //注册驱动 Class.forName("com.mysql.jdbc.Driver"); //获取数据库的连接对象 conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/guo01?useUnicode=true&characterEncoding=utf-8&useSSL=false", "root", "root"); //定义sql语句 String sql = "create table guo02(id int,name varchar(20))"; //获取执行sql的对象Statement stmt = conn.createStatement(); //获取执行sql int count = stmt.executeUpdate(sql); //处理结果 System.out.println(count); } catch (ClassNotFoundException e) { e.printStackTrace(); } catch (SQLException e) { e.printStackTrace(); }finally { //释放资源 if (stmt !=null){ try { stmt.close(); } catch (SQLException e) { e.printStackTrace(); } } if (conn !=null){ try { conn.close(); } catch (SQLException e) { e.printStackTrace(); } } } } }
JDBC各个类详解_ResultSet_基本使用
ResultsetT结果集对象,封装查询结果
next方法(游标向下移动一行)
getXxx(参数),Xxx代表数据类型。如:int get int(),String getString()
Int :代表列的编号 。从1开始如:getString(1)
String: 代表列的名称。getDouble(balance)
public static void main(String[] args) { Connection conn=null; Statement stmt =null; ResultSet rs =null; try { //注册驱动 Class.forName("com.mysql.jdbc.Driver"); //获取数据库的连接对象 conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/guo01?useUnicode=true&characterEncoding=utf-8&useSSL=false", "root", "root"); //定义sql语句 String sql = "create table guo02(id int,name varchar(20))"; //获取执行sql的对象Statement stmt = conn.createStatement(); //获取执行sql rs = stmt.executeQuery(sql); //6.1让游标向下移动一行 rs.next(); //获取数据 int id = rs.getInt(1); String name = rs.getString("name"); double balance = rs.getDouble(3);
} catch (ClassNotFoundException e) { e.printStackTrace(); } catch (SQLException e) { e.printStackTrace(); }finally { //释放资源 if (stmt !=null){ try { stmt.close(); } catch (SQLException e) { e.printStackTrace(); } } if (conn !=null){ try { conn.close(); } catch (SQLException e) { e.printStackTrace(); } } } } }
Preparedstatement :执行sql的对象
标签:548JDBC,549JDBC,ResultSet,stmt,printStackTrace,sql,catch,null,conn From: https://www.cnblogs.com/agzq/p/16797021.html