ADO.NET快速入门——利用Command对象的ExecuteScalar()方法返回一个数据值

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Linq;
 4 using System.Text;
 5 using System.Threading.Tasks;
 6 using System.Data;
 7 using System.Data.SqlClient;
 8 
 9 namespace ConsoleApplication3
10 {
11     class Program
12     {
13         static void Main(string[] args)
14         {
15             string strConn = @"server=Joe-PC;database=AdventureWorks_WroxSSRS2012;uid=sa;pwd=root";
16             SqlConnection conn = new SqlConnection(strConn);
17 
18             string strCmd = "SELECT COUNT(*) FROM Production.ProductCategory";
19             SqlCommand cmd = new SqlCommand(strCmd, conn);
20 
21             conn.Open();
22 
23             int count = Convert.ToInt32(cmd.ExecuteScalar());// ExecuteScalar返回一个object类型
24 
25             Console.WriteLine("共有{0}行数据。", count);
26 
27             conn.Close();
28         }
29     }
30 }