Question

Sorry for the R101 question.

I have a SQL Server 2008 table with a list of items (itemID, Title). I have another table with boxes (boxID, Title). I then have a lookup table that identifies which items go into which boxes.

What is the best way to list all the items with a checkbox checked to show which items are in a box depending on a selected boxID?

Probably a T-SQL statement would be better than a convoluted C# datatable. I’ve had a few attempts but just cant get the right result.

EDIT: Sorry I’ve not been very clear. I need to present a list of all items with a checkbox next to each item. I want checkbox.checked against any item where the boxID has an equivalent item ID next to it in the lookup table.

The result should have have ideally the itemID, itemName and a boolean column to show whether to check the checkbox or not.

The idea is that when the ‘box’ is being updated items can be amended etc.

Answer 1

I suppose you want two things:

1) A list of all items

2) A list of all items in boxes

You can do this in a couple of ways (I’m guessing the structure of your tables here – I’m guessing ItemBox is the link table)

a) Select all of the items, then select a list of all of the items in boxes:

SELECT I.ItemID,
       I.Title,
       B.BoxId,
       B.Title

FROM   Item I
INNER JOIN ItemBox IB ON (I.ItemID = IB.ItemID)
INNER JOIN Box B ON (IB.BoxID = B.BoxID)

ORDER BY B.Title, I.Title   

Should give you all of the items and their boxes.

You can then display a list of all items in a form, and a list of box ids (just simple selects from each table).

If you cache the results from the above query (in say a dictionary, BoxItem dictionary) then you can look up the item quite simply based on the selected Box.

b) you can run the query each time a box is selected:

SELECT I.ItemID,
       I.Title,
       B.BoxId,
       B.Title

FROM   Item I
INNER JOIN ItemBox IB ON (I.ItemID = IB.ItemID)
INNER JOIN Box B ON (IB.BoxID = B.BoxID)

WHERE B.Id = @selected_boxid

ORDER BY B.Title, I.Title   

And update accordingly.

Do you need examples for running the query, binding to various controls etc?

Here’s a version that should do what you want based on your comment:

SELECT I.ItemID,
      I.Title,
        CASE 
           WHEN IB.ItemID IS NULL THEN 0
           ELSE 1
         END AS ItemIsInBox


FROM   Item I
LEFT OUTER JOIN ItemBox IB ON (I.ItemID = IB.ItemID);