JDBC增刪改查--資料庫增加刪除、更新、尋找執行個體

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.建立串連conn=JdbcUtils.getConnection();//單例設計模式conn=JdbcUtilsSingle.getInstance().getConnection();//3.建立語句st=conn.createStatement();//4.執行語句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.建立串連conn=JdbcUtils.getConnection();//單例設計模式conn=JdbcUtilsSingle.getInstance().getConnection();//3.建立語句st=conn.createStatement();//4.執行語句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.建立串連conn=JdbcUtils.getConnection();//單例設計模式conn=JdbcUtilsSingle.getInstance().getConnection();//3.建立語句st=conn.createStatement();//4.執行語句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.建立串連conn=JdbcUtils.getConnection();//單例設計模式conn=JdbcUtilsSingle.getInstance().getConnection();//3.建立語句st=conn.createStatement();//4.執行語句resultset=st.executeQuery("select id,name,birthday,money from user");//5.處理結果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.釋放資源try{if(resultset!=null)resultset.close();} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}finally{try{if(st!=null)st.close();} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}finally{if(conn!=null)try {conn.close();} catch (SQLException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}}}