3月9日 连接数据库（简单的增删改查）

1、增加：

//增加
   private void button2_Click(object sender, EventArgs e)
   {
        string uname=textBox2.Text;
       string upass=textBox1.Text;

SqlConnection conn = new SqlConnection("server=.;database=data1220;user=sa;pwd=sa");
       conn.Open();

SqlCommand cmd = conn.CreateCommand();
       cmd.CommandText = "insert into table1 values(‘"+uname+"‘, ‘"+upass+"‘)";

int count=cmd.ExecuteNonQuery();
       if (count > 0)
       {
           MessageBox.Show("增加成功");
       }
       else
       {
           MessageBox.Show("增加失败");
       }
       conn.Close();
   }

执行结果：

2、删除

//删除
       private void button4_Click(object sender, EventArgs e)
       {
           string code = textBox3.Text;

SqlConnection conn = new SqlConnection("server=.;database=data1220;user=sa;pwd=sa");
           conn.Open();

SqlCommand cmd = conn.CreateCommand();
           cmd.CommandText = "delete from table1 where code="+code;
           cmd.ExecuteNonQuery();
           conn.Close();
       }

3、修改

//修改
   private void button3_Click(object sender, EventArgs e)
   {
       string uname = textBox2.Text;
       string upass = textBox1.Text;
       string code = textBox3.Text;

SqlConnection conn = new SqlConnection("server=.;database=data1220;user=sa;pwd=sa");
       conn.Open();

SqlCommand cmd = conn.CreateCommand();
       cmd.CommandText = "update table1 set uname=‘"+uname+"‘,upass=‘"+upass+"‘where code="+code;
       int count=cmd.ExecuteNonQuery();
       if (count > 0)
       {
           MessageBox.Show("修改成功");
       }
       else
       {
           MessageBox.Show("修改失败");
       }
       conn.Close();
   }

4、查询

//查询
       private void button1_Click(object sender, EventArgs e)
       {
           string uname=textBox2.Text;
           string upass=textBox1.Text;
           //连接数据库
           SqlConnection conn = new SqlConnection("server=.;database=data1220;user=sa;pwd=sa");
           conn.Open();
           //写执行语句
           SqlCommand cmd = conn.CreateCommand();  //通过conn创建SqlCommand对象
           cmd.CommandText = "select *from table1 where uname=‘"+uname+"‘ and upass=‘"+upass+"‘ ";
           SqlDataReader dr = cmd.ExecuteReader();  //执行查询，返回SqlDataReader对象

if (dr.Read())
           {
               MessageBox.Show("登陆成功");
           }
           else
           {
               MessageBox.Show("登陆失败");
           }
           conn.Close();
       }