ExecuteScalar //ExecuteReader

 

//ExecuteScalar的作用  包含的返回值update 如果要得到想要的类型 应该再进行转换

using (SqlConnection conn = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=F:\VS2010\Test\ADO\Database1.mdf;
Integrated Security=True;User Instance=True")) 
            {
                conn.Open();
                using (SqlCommand cmd = conn.CreateCommand())
                {
                    //cmd.CommandText = "select  count (*)from T_User";
                    //Console.WriteLine(cmd.ExecuteScalar());//返回第一行、第一列的数据
                    //返回多行多列？
                    cmd.CommandText = "select * from T_User";
                    Console.WriteLine(cmd.ExecuteScalar());
                }

//ExecuteReader 返回一个结果集

 1  using (SqlConnection conn = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=F:\VS2010\Test\ADO\Database1.mdf;
 2 Integrated Security=True;User Instance=True"))
 3             {
 4                 conn.Open();
 5                 using (SqlCommand cmd = conn.CreateCommand())
 6                 {
 7                     cmd.CommandText = "select * from T_User";
 8                     using (SqlDataReader reader = cmd.ExecuteReader())
 9                     {
10                         while (reader.Read())
11                         {
12                             //Console.WriteLine(reader.GetString(1));
13                             //read.GetOrdinal("UserName") 得到这一列用户名的序号然后reader.GetString得到它的int值
14                             Console.WriteLine(reader.GetString(reader.GetOrdinal("UserName")));
15                             //reader.GetOrdinal("UserName");
16                         }
17                     }
18                 }
19                 Console.WriteLine("OK");
20                 Console.ReadKey();
posted @ 2013-08-23 15:35  -112  阅读(269)  评论(0)  编辑  收藏  举报