命令对象SqlCommand(四)执行语句

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data.SqlClient;

namespace CommandNonQuery
{
    class Program
    {
        static void Main(string[] args)
        {
            SqlConnection conn = new SqlConnection(@"Data Source=.;Initial Catalog=Northwind;Integrated Security=True");
            string sqlqry = @"select count(*) from employees";
            string sqlins=@"insert into employees(firstname,lastname) values('tan','ding')";
            string sqldel = @"delete from employees where firstname='tan' and lastname='ding'";

            SqlCommand cmdqry = new SqlCommand(sqlqry, conn);
            SqlCommand cmdnon = new SqlCommand(sqlins, conn);

            try
            {
                conn.Open();
                Console.WriteLine("Before Insert:Number of employees {0}\n", cmdqry.ExecuteScalar());

                Console.WriteLine("Executing statement {0}", cmdnon.CommandText);
                cmdnon.ExecuteNonQuery();
                Console.WriteLine("After Insert:Number of employees {0}\n", cmdqry.ExecuteScalar());

                cmdnon.CommandText = sqldel;
                Console.WriteLine("Executing statement {0}", cmdnon.CommandText);
                cmdnon.ExecuteNonQuery();
                Console.WriteLine("After Delete:Number of employees {0}\n", cmdqry.ExecuteScalar());
            }
            catch (SqlException ex)
            {
                Console.WriteLine(ex.ToString());
            }
            finally
            {
                conn.Close();
                Console.WriteLine("Connection closed.");
            }
            Console.ReadKey();
        }
    }
}

示例说明：3条SQL语句存放在3个字符串变量中,首先是查询行，然后插入行，最后初始化其CommandText属性，设置删除语句，删除插入的行。