Question

I’ve inherited a less-than-ideal table structure, and I’m trying to improve it as much as I can without tearing down and rebuilding. There’s currently at least two levels of data for everything, the legacy data and the marketing override data. I’m trying to find all the records within the legacy data that don’t yet have a marketing override.

So far, this is what I have:

SELECT DISTINCT    old.STYLE_NBR, old.COLOR_NBR  FROM    LEGACY_PRODUCT_TABLE old INNER JOIN    MARKETING_PRODUCT_TABLE new ON old.STYLE_NBR <> new.style_number AND old.COLOR_NBR <> new.colour_number 

This seems to work, but it takes a few minutes to run. If at all possible, I’d like a more efficient way of doing this.

Other info:

• There are about 60,000 records in the legacy table
• There are about 7,000 in the marketing table
• Both STYLE_NBR and COLOR_NBR are char(5) and, when combined, make a unique ID.

Answer 1

You should be using a LEFT OUTER JOIN and change your lookup

SELECT DISTINCT    old.STYLE_NBR, old.COLOR_NBR  FROM    LEGACY_PRODUCT_TABLE old   LEFT OUTER JOIN MARKETING_PRODUCT_TABLE new     ON (old.STYLE_NBR + old.COLOR_NBR) = (new.style_number + new.Colour_number) WHERE (new.style_number + new.Colour_number) IS NULL