Question

C#中，如何把SQL数据库中的值赋值给我的一个变量中？（例如int a）

我的数据库是这样的，如图，
int a1 = 0;
int a2 = 0;
string MyConn = "Data Source=.;Initial Catalog=sqlstudent;Integrated Security=True";
SqlConnection MyConnection = new SqlConnection(MyConn);
string MyInsert = "insert into Sc_Student(Stu_ID,Stu_Name,Stu_Sex,Class_ID)values('" + Convert.ToString(textBox1.Text) +
"','" + Convert.ToString(textBox2.Text) + "','" + sex + "','" + Convert.ToString(textBox3.Text) + "')";
SqlCommand MyCommand = new SqlCommand(MyInsert, MyConnection);
if (textBox1.Text == "" | textBox2.Text == "" | textBox3.Text == "")
{
MessageBox.Show("请填写完整的学生信息");
this.Close();
studentadd mymodify = new studentadd();
mymodify.Show();
}
if (textBox3.Text == "1020541")
a1 = 1;
if (textBox3.Text == "1020542")
a2 = 1;
try//异常处理
{
MyConnection.Open();
MyCommand.ExecuteNonQuery();
string numConn = "Data Source=.;Initial Catalog=sqlstudent;Integrated Security=True";
SqlConnection numConnection = new SqlConnection(numConn);
if (a1 == 1)
{
string numInsert = "update Sc_Class set Stu_Num=Stu_Num+a1 where Class_ID=1020541";
SqlCommand numCommand = new SqlCommand(numInsert, numConnection);
a1 = 0;
}
if (a2 == 1)
{
string numInsert = "update Sc_Class set Stu_Num=Stu_Num+a2 where Class_ID=1020542";
SqlCommand numCommand = new SqlCommand(numInsert, numConnection);
a2 = 0;
}
MyConnection.Close();
MessageBox.Show("添加成功");

this.Close();

}
catch (Exception ex)
{
Console.WriteLine("{0} Exception caught.", ex);

}
我不知道怎么赋值，就是把表中的1020541的Stu_Num赋值给一个变量，或者说让Stu_Num加上一个数字，例如1，求高手啊

Answer 1

string MyConn = "Data Source=.;Initial Catalog=sqlstudent;Integrated Security=True";
SqlConnection MyConnection = new SqlConnection(MyConn);
String str="select * from Sc_Student";
SqlDataAdapter sqlada=new SqlDataAdapter(str,MyConn);
DataSet myset=new DataSet();
sqlada.Fill(myset);
然后你的Sc_Student表里面的内容都会在myset这个数据集中，用String ss=myset.Table[0].Rows[x][y].ToString();取出你想要的值，X,Y为数据表的Row 和cell

Answer 2

DataTable取出Stu_num,把值赋给一个变量值x,然后 x = x + "1"；

Answer 3

string numInsert = "update Sc_Class set Stu_Num=Stu_Num+1 where Class_ID=1020542";