通常有以下两种方式 SqlDataReader 和SqlDataAdapter|DataSet方式

SqlDataReader 方式使用方式如下：

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

using System.Data.SqlClient;  

namespace Login

{

    class Program

    {

        static void Main(string[] args)

        {

            //新建一个数据库连接

            using(SqlConnection conn = new SqlConnection(GetConnectString()))

            {

                conn.Open();//打开数据库

                //Console.WriteLine("数据库打开成功!");

                //创建数据库命令

                SqlCommand cmd = conn.CreateCommand();

                //创建查询语句

                cmd.CommandText = "SELECT * FROM userinfo";

                //从数据库中读取数据流存入reader中

                SqlDataReader reader = cmd.ExecuteReader();                 

                //从reader中读取下一行数据,如果没有数据,reader.Read()返回flase

                while (reader.Read())

                {

                    //reader.GetOrdinal("id")是得到ID所在列的index,

                    //reader.GetInt32(int n)这是将第n列的数据以Int32的格式返回

                    //reader.GetString(int n)这是将第n列的数据以string 格式返回

                    int id = reader.GetInt32(reader.GetOrdinal("id"));

                    string name = reader.GetString(reader.GetOrdinal("name"));

                    string pwd = reader.GetString(reader.GetOrdinal("password"));

                    int age = reader.GetInt32(reader.GetOrdinal("age"));

                    string sex = reader.GetString(reader.GetOrdinal("sex"));

                    string phone = reader.GetString(reader.GetOrdinal("phone"));

                    string address = reader.GetString(reader.GetOrdinal("Address"));  

                    //格式输出数据

                    Console.Write("ID:{0},Name:{1},PWD:{2},Age:{3},Sex:{4},Phone{5},Address:{6}\n", id, name, pwd, age, sex, phone, address);

                }

            }

            Console.ReadKey();

        }

        //得到一个数据库连接字符串

        static string GetConnectString()

        {

            return "Data Source=(local);Initial Catalog=db1;Integrated Security=SSPI;";

        }

    }

}

SqlDataAdapter|DataSet 方式如下

加入为SQLSERVER数据库：

using System.Data.SqlClient;

using System.Data;

 SqlConnection conn = new SqlConnection(connectionString);

            SqlCommand cmd = new SqlCommand("secelt * from userinfo", conn);

            SqlDataAdapter sda = new SqlDataAdapter(cmd);

            DataSet ds = new DataSet();

            sda.Fill(ds, "table");

            return ds.Tables["table"];//返回的是一个DataTable