package com.bict;
import java.sql.*;
public class Common {
    /*獲取數據庫連接*/
    public static Connection getConnection(){
          Connection con=null;
          try{
              Class.forName("org.gjt.mm.mysql.Driver");
              String str="jdbc:mysql://localhost:3306/test";
              con=DriverManager.getConnection(str,"root","");
          }catch(Exception e){
              e.printStackTrace();
          }
          return con;
    }
    /*釋放數據庫連接*/
    public static void freeConnection (Connection con){
         if(con!=null){
            try {
                con.close();
            } catch(SQLException ex) {
                ex.printStackTrace();
            }
         }
    }
    /*運行非更新型SQL語句*/
    public static ResultSet executeQuery(String sql){
        ResultSet rs=null;
        Connection con=getConnection();
        try {
            Statement st = con.createStatement();
            rs=st.executeQuery(sql);
        } catch(SQLException ex) {
            ex.printStackTrace();
        }finally{
            freeConnection(con);
        }
        return rs;
    }
    /*運行更新型SQL語句,比如更新記錄,刪除記錄,添加記錄等*/
    public static void executeUpdate(String sql){
        Connection con=getConnection();
        try {
            Statement st = con.createStatement();
            st.executeUpdate(sql);
        } catch(SQLException ex) {
            ex.printStackTrace();
        }finally{
            freeConnection(con);
        }

    }
    /*獲取查詢結果的記錄數*/
    public static int getResultCount(String sql){
         int result=-1;
         ResultSet rs=executeQuery(sql);
        try {
            rs.last();
            result=rs.getRow();
        } catch(SQLException ex) {
            ex.printStackTrace();
        }
         return result;
    }

}