Question

I am using 3 tables for this, Part, PartDrawing and ShopDrawing. Basically I want to display all ShopDrawings where all their Parts are in stock. However each ShopDrawing has multiple PartDrawings that go with it so when I run my query like this:

SELECT DISTINCT ShopDrawing.DrawingNo FROM ShopDrawing, PartDrawing, Part
WHERE ShopDrawing.DrawingNo = PartDrawing.DrawingNo
AND PartDrawing.PartNo = Part.PartNo
AND Part.InStock = 'YES';

It displays every single ShopDrawing because they all have at least one Part that is in stock. I only want want it to display the ShopDrawings where all the Parts that are needed for it are in stock, and I’m not sure how to do this.

Answer 1

Try to evaluate by not select data with Part.InStock = 'NO' rather than select data with Part.InStock = 'YES'

SELECT 
     ShopDrawing.DrawingNo 
FROM 
     ShopDrawing WHERE ShopDrawing.DrawingNo NOT IN
         (SELECT 
              PartDrawing.DrawingNo 
          FROM 
              PartDrawing LEFT JOIN Part ON PartDrawing.PartNo = Part.PartNo 
          WHERE 
              Part.InStock IS NULL
          GROUP BY PartDrawing.DrawingNo 
          HAVING COUNT(*)>0)