C#为连接sql server数据库,写个DBHelper类

Roc posted @ 2010年6月25日 08:01 in C# , 7684 阅读

 

在DBHelper类中

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.SqlClient;
namespace MySchool                                                                     //MySchool是我的项目名称
{
    class DBHelper
    {
        static string conString = "Data Source=服务器名;Initial Catalog=数据库名;User ID=sa";                                        //我选择的是windows+sql混合验证,登录名sa,如果有Pwd还需要添加
        public static SqlConnection con=new SqlConnection(conString);                                                                                //创建SqlConnection对象,用于连接
    }
}

 

然后在另一个类中(比如窗体类)可以调用
using System.Data.SqlClient;
string sql = "select * from teacher";                                                                       //输入的sql命令
SqlCommand cmd = new SqlCommand(sql,DBHelper.con);                        //创建SqlCommand对象,导入sql命令,连接的是DBHelper中写好的数据库
DBHelper.con.Open();                                                                                             //打开数据库
SqlDataReader dr = cmd.ExecuteReader();                                                       //创建SqlDataReader类对象,用于一行一行读取数据库中数据
dr.HasRows                                                                        //在数据库中执行select * from teacher,会有多行受到影响。如果有影响,HasRows返回true,否则返回false
dr.Read();                                                                                //读取一行数据,若想一遍一遍的读,一直到读完为止,则可以写到while语句中
string loginid = dr["LoginID"].ToString();                            //把数据库中字段LoginID的第一个记录给字符串loginid
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