SQL Query comparison (Use as variable)

Question

I have two queries:

SELECT * FROM postcodelatlng, shops WHERE shops.postcode=postcodelatlng.postcode;

SELECT * FROM postcodelatlng, tesco WHERE tesco.postcode=postcodelatlng.postcode;

idea is that I would like to use lat and lng from first query and use it as variable as lat1 and lng1

and the take second query and use the same way to get lat2 and lng2

Finally i should have like ($lat1, $lng1, $lat2, $lng2) (Start point vs End point)

Answer 1

I believe you are looking sth like:

SELECT *
FROM postcodelatlng
INNER JOIN tesco ON tesco.postcode = postcodelatlng.postcode
WHERE postcodelatlng.lat IN (
        SELECT lat
        FROM postcodelatlng
        INNER JOIN shops
        WHERE shops.postcode = postcodelatlng.postcode
        )
    AND postcodelatlng.lng IN (
        SELECT lng
        FROM postcodelatlng
        INNER JOIN shops
        WHERE shops.postcode = postcodelatlng.postcode
        )