How to find the values that never matched in a full join

Question

Hello I have done this full join query:

SELECT
  F.date AS Campaign_Date,
  F.Store AS AS Campaign_Store,
  F.IMPRESSIONS,
  F.CLICKS,
  F.SPEND,
  C.Date AS visitors_Date,
  C.ANNEE_MOIS,
  C.ANNEE,
  C.MOIS,
  C.Store AS visitors_Store,
  C.FREQUENTATION_Store
FROM
  `project.campaigns`  F
FULL JOIN
  `proiject.visitors` C
ON (
  C.Store= F.Store
  AND C.Date =F.date
  )

And now, I want to retireve that values of column FRQ_Store that never matched any of those Campaign_Store ! In other words, how can I retrieve all the value of two columns that never matched in a full join query ?

Thank you!

Answer 1

What you appear to want is a left outer join on NULL, this will give you only the rows of the left table which do not have a match with the right table:

SELECT    F.Store
FROM      `project.campaigns`  F
LEFT JOIN `project.visitors`   C
ON (
      F.Store = C.Store
  AND F.Date  = C.Date
  )
WHERE C.Store IS NULL