C# ado.net基础 查询一个表中有多少行数据 在sqlsever中的一个表中

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 using System.Threading.Tasks;
 6 
 7 namespace shujuku
 8 {
 9     class SqlInformation
10     {
11         /// <summary>
12         /// 服务器的名称
13         /// </summary>
14         public string DataSource;
15         /// <summary>
16         /// 数据库的名称
17         /// </summary>
18         public string InitialCatalog;
19         /// <summary>
20         /// true为使用windows验证
21         /// </summary>
22         public bool IntegratedSecurity;
23         /// <summary>
24         /// SqlServer身份验证所需要的用户名
25         /// </summary>
26         public string UserID;
27         /// <summary>
28         /// SqlServer身份验证所需要的密码
29         /// </summary>
30         public string Password;
31         /// <summary>
32         /// 返回连接字符串
33         /// </summary>
34         public SqlInformation()
35         {
36             IntegratedSecurity = false;
37         }
38         public string LoginInformation()
39         {
40             if (IntegratedSecurity)
41             {
42                 return string.Format(@"Data Source = {0}; Initial Catalog = {1}; Integrated Security = true", DataSource, InitialCatalog);
43             }
44             else
45             {
46                 return string.Format(@"Data Source = {0};Initial Catalog = {1};User ID = {2};Password = {3}", DataSource, InitialCatalog, UserID, Password);
47             }
48         }
49     }
50 }

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Data.SqlClient;
 4 using System.Linq;
 5 using System.Text;
 6 using System.Threading.Tasks;
 7 
 8 namespace shujuku
 9 {
10     class Program
11     {
12         static void Main(string[] args)
13         {
14             SqlInformation test = new SqlInformation();
15             test.DataSource = "USER-20170116MG";
16             test.InitialCatalog = "helloworld";
17             test.IntegratedSecurity = true;
18             string conStr=test.LoginInformation();
19 
20             using (SqlConnection connection = new SqlConnection(conStr))
21             {
22                 //编写sql语句(可以在sql server中创建脚本尝试成功后，复制粘贴)
23                 string sql = "select count(*) from TeacherClass";
24                 //创建一个执行sql语句的对象
25                 using (var cmd =new SqlCommand())
26                 {
27                     cmd.CommandText = sql;
28                     cmd.Connection = connection;
29                     //打开连接
30                     connection.Open();
31                     Console.WriteLine("数据库连接成功");
32                     int count = Convert.ToInt32(cmd.ExecuteScalar());
33                     Console.WriteLine("表的数据共有：{0}行",count);
34                     Console.WriteLine("sql语句执行成功");
35                 }
36                 //关闭连接，释放资源.因为用了 using，所以这里不用写语句
37             }
38             Console.WriteLine("数据库断开成功");
39             Console.ReadKey();
40 
41         }
42     }
43 }