数据库简单增删改查

namespace 数据库增删改查

{

    public partial class Form1 : Form

    {

        public Form1()

        {

            InitializeComponent();

        }



        private void button1_Click(object sender, EventArgs e) //登陆(查询)

        {

            string user = textBox2.Text;

            string password = textBox3.Text;



            SqlConnection coon = new SqlConnection("server=.;database=enter;user=sa;pwd=123"); //连接数据库

            coon.Open();//打开数据库

            SqlCommand cmd = coon.CreateCommand();//执行查询语句

            cmd.CommandText = "select * from enters where username='"+user+"' and userpass='"+password+"'"; //进行匹配

            SqlDataReader dr = cmd.ExecuteReader();//执行查询，将结果反馈给dr

            if (dr.Read())

            {

                MessageBox.Show("登陆成功");

            }

            else

            {

                MessageBox.Show("登陆失败");

            }

            coon.Close();



        }



        private void button3_Click(object sender, EventArgs e) //添加

        {

            string user = textBox2.Text;

            string password = textBox3.Text;

            SqlConnection coon = new SqlConnection("server=.;database=enter;user=sa;pwd=123");

            coon.Open();

            SqlCommand cmd = coon.CreateCommand();

            cmd.CommandText = "insert into enters values('"+user+"','"+password+"')";

            int count = cmd.ExecuteNonQuery();//增删改都用这个

            if(count>0)

            {

                MessageBox.Show("添加成功");

            }

            coon.Close();

        }



        private void button2_Click(object sender, EventArgs e) //修改

        {

            string code = textBox1.Text;

            string user = textBox2.Text;

            string password = textBox3.Text;

            SqlConnection coon = new SqlConnection("server=.;database=enter;user=sa;pwd=123");

            coon.Open();

            SqlCommand cmd = coon.CreateCommand();

            cmd.CommandText = "update enters set username='"+user+"' , userpass='"+password+"' where code="+code;

            int count = cmd.ExecuteNonQuery();

            if(count>0)

            {

                MessageBox.Show("修改成功");

            }

            else

            {

                MessageBox.Show("修改失败！");

            }

            coon.Close();

        }



        private void button4_Click(object sender, EventArgs e) //删除

        {

            string code = textBox1.Text;

            SqlConnection coon = new SqlConnection("server=.;database=enter;user=sa;pwd=123");

            coon.Open();

            SqlCommand cmd = coon.CreateCommand();

            cmd.CommandText = "delete from enters where code="+code;

            cmd.ExecuteNonQuery();

            coon.Close();

        }

    }

}