保存/检索/比较DB中的CheckboxList值

Question

I am not sure if what i want is possible, but so far i have had no luck...

I am using Visual Studio, asp.net and SQL. a field in table in varchar(max) type...

What I want to do is save the values of CheckBoxList into the database and retrieve them to compare them in a SQL command to filter a few values from the table in database.

It's easier to understand when I give an example:

So I have these in HTML side of the code.

<asp:CheckBoxList ID="CheckBoxList1" runat="server" onselectedindexchanged="CheckBoxList1_SelectedIndexChanged">
        <asp:ListItem Value="1">Sales</asp:ListItem>
        <asp:ListItem Value="2">Administration</asp:ListItem>
        <asp:ListItem Value="3">Help</asp:ListItem>
</asp:CheckBoxList>

This in code to save the data

protected void CheckBoxList1_SelectedIndexChanged(object sender, EventArgs e)
{
        TextBox20.Text = "";
        string s = null;

        for (int i = 0; i < CheckBoxList1.Items.Count; i++)
        {
            if (CheckBoxList1.Items[i].Selected)
                s += CheckBoxList1.Items[i].Value + ",";

            TextBox20.Text = s;
        }
    }

Now when some one chooses like two options, example Sales and Administration , I want the values 1,2 to be stored in the database in a single column.

Then retrieve the values, using SQL show rows which have Sales or Administration / Sales and Administration in the column I want.

I am not sure whether I am going about this the right way.. But any help would be appreciated.... I read that creating a table with all the values i need is they correct way.. but i dunno how it works..

Answer 1

Firstly, I would recommend the use of the StringBuilder class for doing string concatenation inside a loop as it is much more efficient -

For routines that perform extensive string manipulation (such as apps that modify a string numerous times in a loop), modifying a string repeatedly can exact a significant performance penalty. The alternative is to use StringBuilder, which is a mutable string class.

MSDN StringBuilder Class Documentation

I agree with the comment above made by HABO, storing comma seperated values in a single column is almost always a bad idea. You should probably create a class called User. Give the User class properties such as 'name' and 'roles'.

With regards to the database structure for this data, once again I agree with HABO, two tables would be recommended. User and UserRoles. In the User table you would store data such as Id, Username, Age, etc. you can then in the UserRoles table store UserId (the Id from the User table), in this way a User can be assigned multiple roles.

If you want more detail feel free to ask and I'll try and provide example schema etc.