winform数据库调用（基本方法）

//向数据库中新增数据　
　　　　private void button1_Click_1(object sender, EventArgs e)
        {
            SqlConnection conn = new SqlConnection("server=.;database=作业;user=sa;pwd=123");
            SqlCommand cmd = conn.CreateCommand();
            cmd.CommandText = "insert into student values(@sno,@sname,@ssex,@sbirthday,@class)";
            cmd.Parameters.Clear();
            cmd.Parameters.Add("@sno",textbox1.Text.Trim());
            cmd.Parameters.Add("@sname", textbox2.Text.Trim());
            if (rbtnan.Checked)
            {
                cmd.Parameters.Add("@ssex", "男");
            }
            else
            {
                cmd.Parameters.Add("@ssex", "女");
            }
            cmd.Parameters.Add("@sbirthday", dateTimePicker1.Value);
            cmd.Parameters.Add("@class", comboBox1.Text.Trim());
            conn.Open();
            int count = cmd.ExecuteNonQuery();
            if (count > 0)
            {
                MessageBox.Show("执行成功，受影响行数为：" + count.ToString());
            }
            else
            {
                MessageBox.Show("执行失败！");
            }
            conn.Close();
        }

//修改数据库中的数据
　　　　  private void button1_Click(object sender, EventArgs e)
        {
            SqlConnection conn = new SqlConnection("server=.;database=作业;user=sa;pwd=123");
            SqlCommand cmd = conn.CreateCommand();
            cmd.CommandText = "update student set sname=@sname,ssex=@ssex,sbirthday=@sbirthday,class=@class where sno=@sno";
            cmd.Parameters.Clear();
            cmd.Parameters.Add("@sno", textbox1.Text.Trim());
            cmd.Parameters.Add("@sname", textbox2.Text.Trim());
            if (rbtnan.Checked)
            {
                cmd.Parameters.Add("@ssex", "男");
            }
            else
            {
                cmd.Parameters.Add("@ssex", "女");
            }
            cmd.Parameters.Add("@sbirthday", dateTimePicker1.Value);
            cmd.Parameters.Add("@class", comboBox1.Text.Trim());
            conn.Open();
            int count = cmd.ExecuteNonQuery();
            if (count > 0)
            {
                MessageBox.Show("执行成功，受影响行数为：" + count.ToString());
            }
            else
            {
                MessageBox.Show("执行失败！");
            }
            conn.Close();
        }

//删除数据库中的数据
　　　　  private void button1_Click(object sender, EventArgs e)
        {
            SqlConnection conn = new SqlConnection("server=.;database=作业;user=sa;pwd=123");
            SqlCommand cmd = conn.CreateCommand();
            cmd.CommandText = "Delete from student where sno=@sno";
            cmd.Parameters.Clear();
            cmd.Parameters.Add("@sno", textbox1.Text.Trim());
            conn.Open();
            int count = cmd.ExecuteNonQuery();
            if (count > 0)
            {
                MessageBox.Show("执行成功，受影响行数为：" + count.ToString());
            }
            else
            {
                MessageBox.Show("执行失败！");
            }
            conn.Close();
        }

//查询数据库中的数据
　　　　  private void button1_Click(object sender, EventArgs e)
        {
            SqlConnection conn = new SqlConnection("server=.;database=作业;user=sa;pwd=123");
            SqlCommand cmd = conn.CreateCommand();
            DataTable dt = new DataTable();
            cmd = conn.CreateCommand();
            cmd.CommandText = "select * from student";
            conn.Open();
            SqlDataReader dr = cmd.ExecuteReader();
            for (int i = 0; i < dr.FieldCount; i++)
            {
                dt.Columns.Add(dr.GetName(i));
            }
            while (dr.Read())
            {
                DataRow row = dt.NewRow();
                row["sno"] = dr["sno"];
                row["sname"] = dr["sname"];
                row["ssex"] = dr["ssex"];
                row["sbirthday"] = dr["sbirthday"];
                dt.Rows.Add(row);
            }
            conn.Close();        
        }