C# 查询一个值方法ExecuteScalar()

需要从SQL查询中返回一个值，如表中记录数。可以使用ExecuteScalar()方法，这个方法只返回一个值。如下边控制台应用程序代码所示：

using System.Data;

using System.Data.SqlClient;

namespace ExecuteScalar

{

class Program

{

static void Main(string[] args)

{

SqlConnection thisConnection = new SqlConnection(

@"Data Source=scott;Initial Catalog=northwind;Persist Security Info=True;User ID=sa;Password=sa123");

thisConnection.Open();

SqlCommand thisCommand = thisConnection.CreateCommand();

thisCommand.CommandText = "select count(*) from customers";

//ExecuteScalar：执行只返回一个值的SQL命令。

object countResult = thisCommand.ExecuteScalar();

Console.WriteLine("Count of Customers={0}",countResult);

Console.ReadLine();

thisConnection.Close();

}

}

}

结果为：

Count of Customers=91