Parse & Compare Data using Coldfusion & MySQL

Question

First, I\'ll explain what I need to do, then how I think I can achieve it. My current plan seems very inefficient in theory, so my question is whether there is a b

Answer 1

For finding the changes, I'd look at joins based on the fields you want to match on. This can be slow, depending on the number of fields and whether or not they're indexed, but I'd still say it was faster than loops. Something along the lines of:

SELECT product_id
FROM Products
WHERE product_id NOT IN (
    SELECT T.product_id
    FROM Products_Temp T
    INNER JOIN PRODUCTS P
    ON (
        P.field1 = T.field1
        AND P.field2 = T.field2
        ...
    )
)

For the missing products to find the non-matches:

SELECT P.product_id
FROM Products P
LEFT OUTER JOIN Products_Temp T
ON (P.field1 = T.field1
    AND P.field2 = T.field2
    ...)
WHERE T.product_id IS NULL