c# - 如何选择一列中除一个值之外的所有数据？

Question

我编写了这个 c# 代码来从学生信息中选择 card_id，除了一个 card_id，但我从网上读到 except 子句在访问中不起作用……我该怎么做，请帮帮我？

ol_com.CommandText = "select [card_id] from student_info except select [card_id] from student_info where [card_id] = '"+update_st_card.Text+"'";
                reader = ol_com.ExecuteReader();
                if (reader.HasRows)
                {
                    up_st_lbl2.Text = "message";
                }

Answer 1

我认为您不必要地进行复杂查询。

它可以很容易地使用NOT IN

ol_com.CommandText = "select [card_id] from student_info 
where [card_id] not in ('"+update_st_card.Text+"')";

Answer 2

您在插入时没有问题，所以要更新，请尝试这个简单的。update_st_card.Text 只有一个 card_Id。

ol_com.CommandText = "select [card_id] from student_info 
where [card_id] ='"+update_st_card.Text+"'";
reader = ol_com.ExecuteReader();
string str=string.Empty();
if (reader.HasRows)
{
  //Update here
    str="Update student_info set mobile_no='Your new value to set'
             where [card_id] ='"+update_st_card.Text+"'";

}
else
{
  //insert here
    str="Your Insert command";
}
ol_com.CommandText = str;
ol_com.ExecuteNonQuery();

Answer 3

我认为这将解决您的问题，我们可以不在任何地方使用访问、sql server、nhibernate

ol_com.CommandText = "select [card_id] from student_info where [card_id] not in ( select [card_id] from student_info where [card_id] = '"+update_st_card.Text+"'");
reader = ol_com.ExecuteReader();
if (reader.HasRows)
{
   up_st_lbl2.Text = "message";
}

Answer 4

我认为你可以使用 NOT IN

您的查询可以写成，

select [card_id] 
from student_info 
where [card_id] NOT IN 
 (select [card_id] from student_info where [card_id] = '"+update_st_card.Text+"'")