myeclipse链接数据库，SQL语句实现增删改查

最新推荐文章于 2021-04-13 14:13:33 发布

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本文介绍如何使用Java的JDBC技术进行数据库连接配置，包括properties文件设置、数据库连接类编写及数据库查询操作示例。通过具体代码展示，帮助读者理解JDBC的工作流程和常见错误处理。

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1、创建properties文件

#oracle
#driver=oracle.jdbc.OracleDriver
#url=jdbc\:oracle\:thin\:@localhost\:1521\:xe
#username=system
#password=manager

#mysql
driver=com.mysql.jdbc.Driver
url=jdbc\:mysql\://192.168.0.121\:3306/test?user\=root&password\=root&characterEncoding\=utf8
username=root
password=root

2、创建链接数据库类

public class JdbcConnect {
private static Properties prop = new Properties();
   static{

       try {
       //Properties prop = new Properties();
               prop.load(Thread.currentThread().getContextClassLoader().getResourceAsStream("jdbc.properties"));
           Class.forName(prop.getProperty("driver"));
               //Class.forName(prop.getProperty("mysqlDriver"));
       } catch (Exception e) {
               // TODO Auto-generated catch block
           System.out.println("Error");
               e.printStackTrace();
           }

   }


   public static Connection getConn(){
   Connection conn =null;
       try {
           //Oracle
           conn = DriverManager.getConnection(prop.getProperty("url"),
           prop.getProperty("username"),prop.getProperty("password"));
           //Mysql
           //conn = DriverManager.getConnection(prop.getProperty("mysqlUrl"));
           //System.out.println(conn);
       } catch (SQLException e) {
           // TODO Auto-generated catch block
           e.printStackTrace();
       }finally{

       }
   return conn;


   }


   public static void close(Connection conn,PreparedStatement pstmt,ResultSet rs){
       try {
               if(pstmt != null)
                   pstmt.close();
               if(rs != null)
                   rs.close();
               if(conn != null)
                   conn.close();
           } catch (Exception e) {
               e.printStackTrace();
               // TODO: handle exception
           }

   }
//   public static void main(String[] args) {
//           new JdbcConnect().getConn();
//       }
}

3、测试访问数据库

初始化

private Connection conn = null;
private PreparedStatement pstmt = null;
private ResultSet rs = null;

访问

   //查询总记录
   public int queryCount() {
       int count =0;
       try {
           conn = MyJdbcConnect.getConn();
//           pstmt = conn.prepareStatement("select count(*) from student");
           pstmt = conn.prepareStatement("select max(age) as avgvalue from userinfodz");
           rs = pstmt.executeQuery();
           if(rs.next()){
               count = rs.getInt(1);
           }
       } catch (Exception e) {
           // TODO: handle exception
           e.printStackTrace();
       }finally{
           MyJdbcConnect.close(conn, pstmt, rs);
       }
       return count;
   }

附：

public interface SQLSentence {
String oinsert="insert into mytable values(mytab_seq.nextval,?,?,?,?,?)";
String minsert="insert into mytable values(null,?,?,?,?,?)";
String update="update mytable t set t.myname=? ,t.myage=?,t.myhobby =?,t.myinfo=? where t.myid=?";
String delete="delete from mytable where myid=?";
String qcount="select count(*) from mytable";
String Pagingfororacle="select * from(select T.*,ROWNUM RN from MyTable T where ROWNUM<=? order by T.myid) where RN>=?";
String Pagingformysql=" select * from mytable limit ? , ?";
String PagingforOracle2 = "select * from(select T.*,ROWNUM RN from MyTable T order by T.myid) where RN between ? and ?";
String GetMyTableById = "select * from mytable where myid = ?";

}