最简单的手工写增删改查的代码

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

namespace ConsoleApplication2
{
    class Program
    {
        static void Main(string[] args)
        {
            String sql;
            int result=0;

            //最简单的手工写增，删，改，查
            //辅助记忆， 服务器=.;用户名＝;密码=;数据库=;
            string connectionString = "server=.;uid=sa;pwd=flower520;database=Stu;";
            SqlConnection con = new SqlConnection(connectionString);

            //1.增加
            sql = "insert into Student (Name,Age,Memo) values('小明',20,'好玩');select SCOPE_IDENTITY()";
            SqlCommand cmd = new SqlCommand(sql, con);
            con.Open();
            result = Convert.ToInt32(cmd.ExecuteScalar());
            Console.WriteLine(result > 0 ? "添加成功！" : "添加失败！");

            //2.删除
            sql = "delete from Student where id=2";
            cmd.CommandText = sql;
            result = cmd.ExecuteNonQuery();
            Console.WriteLine(result > 0 ? "删除成功！" : "删除失败！");

            //3.修改
            sql = "update Student set name='小刘' where id=4";
            cmd.CommandText = sql;
            result = cmd.ExecuteNonQuery();
            Console.WriteLine(result>0?"修改成功！":"修改失败！");

            //4.查询
            sql = "select * from Student";
            cmd.CommandText = sql;
            SqlDataReader dr = cmd.ExecuteReader();
            while (dr.Read()) {
                Console.WriteLine(string.Format("{0}  {1}  {2} {3}",dr[0],dr[1],dr[2],dr[3]));
            }
            //注， 此时必须关闭dr, 因为dr是独占的， 如果不关闭， 会造成其它操作无法进行。
            dr.Close();

            //另一种查询的方法
            SqlDataAdapter da = new SqlDataAdapter(sql, con);
            DataSet ds = new DataSet();
            da.Fill(ds, "table1");
            DataTable dt = ds.Tables["table1"];
            Console.WriteLine("\n另一种查询方式：");
            foreach (DataRow dRow in dt.Rows) {
                Console.WriteLine(string.Format("{0}  {1}  {2} {3}", dRow[0], dRow[1], dRow[2], dRow[3]));
            }

            Console.ReadLine();
        }
    }
}