JDBC增删改查--数据库增加删除、更新、查找实例

 package cn.com.JDBC;

 import java.sql.Connection;
 import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.sql.Statement;

 public class CRUD {

     public static void main(String[] args) throws SQLException {
         // TODO Auto-generated method stub
         //create();
         //update();
         delete();
         read();
     }
     static void delete() throws SQLException
     {
         Connection conn=null;
         Statement st=null;
         ResultSet resultset=null;

         try {
             //2.建立连接
             conn=JdbcUtils.getConnection();
             //单例设计模式
             conn=JdbcUtilsSingle.getInstance().getConnection();
             //3.创建语句
             st=conn.createStatement();
             //4.执行语句
             String sql="delete from user where id>5";
             int i=st.executeUpdate(sql);

             System.out.println("i="+i);
         } finally
         {
             JdbcUtils.free(resultset, st, conn);
         }
     }
     static void update() throws SQLException
     {
         Connection conn=null;
         Statement st=null;
         ResultSet resultset=null;

         try {
             //2.建立连接
             conn=JdbcUtils.getConnection();
             //单例设计模式
             conn=JdbcUtilsSingle.getInstance().getConnection();
             //3.创建语句
             st=conn.createStatement();
             //4.执行语句
             String sql="update user set money=money+20";
             int i=st.executeUpdate(sql);

             System.out.println("i="+i);
         } finally
         {
             JdbcUtils.free(resultset, st, conn);
         }
     }
     static void create() throws SQLException
     {
         Connection conn=null;
         Statement st=null;
         ResultSet resultset=null;

         try {
             //2.建立连接
             conn=JdbcUtils.getConnection();
             //单例设计模式
             conn=JdbcUtilsSingle.getInstance().getConnection();
             //3.创建语句
             st=conn.createStatement();
             //4.执行语句
             String sql="insert into user(name,birthday,money) values('wy','2011-09-23','2894656')";
             int i=st.executeUpdate(sql);

             System.out.println("i="+i);
         } finally
         {
             JdbcUtils.free(resultset, st, conn);
         }
     }
     static void read() throws SQLException
     {
         Connection conn=null;
         Statement st=null;
         ResultSet resultset=null;

         try {
             //2.建立连接
             conn=JdbcUtils.getConnection();
             //单例设计模式
             conn=JdbcUtilsSingle.getInstance().getConnection();
             //3.创建语句
             st=conn.createStatement();
             //4.执行语句
             resultset=st.executeQuery("select id,name,birthday,money from user");
             //5.处理结果
             while(resultset.next())
             {
                 System.out.println(resultset.getObject("id"));
                 System.out.println(resultset.getObject("name"));
                 System.out.println(resultset.getObject("birthday"));
                 System.out.println(resultset.getObject("money"));
             }

         } finally
         {
             JdbcUtils.free(resultset, st, conn);
         }
     }
 }
 package cn.com.JDBC;

 import java.sql.Connection;
 import java.sql.DriverManager;
 import java.sql.ResultSet;
 import java.sql.SQLException;
 import java.sql.Statement;

 public class JdbcUtils
 {
     private static String url="jdbc:mysql://localhost:3306/jdbc";
     private static String user="root";
     private static String password="123";
     private JdbcUtils()
     {
     }
     static
     {
         try
         {
             Class.forName("com.mysql.jdbc.Driver");
         }
         catch(ClassNotFoundException e)
         {
             throw new ExceptionInInitializerError(e);
         }
     }
     public static Connection getConnection() throws SQLException
     {
         return DriverManager.getConnection(url, user, password);
     }
     public static void free(ResultSet resultset,Statement st,Connection conn)
     {
         //6.释放资源
         try{
         if(resultset!=null)
             resultset.close();
         } catch (SQLException e) {
             // TODO Auto-generated catch block
             e.printStackTrace();
         }
         finally
         {
             try
             {
                 if(st!=null)
                     st.close();
             } catch (SQLException e) {
                 // TODO Auto-generated catch block
                 e.printStackTrace();
             }
             finally
             {
                 if(conn!=null)
                     try {
                         conn.close();
                     } catch (SQLException e) {
                         // TODO Auto-generated catch block
                         e.printStackTrace();
                     }
             }
         }
     }
 }