php - mysql union does not add up all the results

Question

I have the following two queries:

SELECT scan, mrn, ecd, babyName, badgeNumber, 'dummy' as verifiedBy, 
       adLogin, ts, 'dummy' as reason 
FROM (`Verifications`) 
LEFT JOIN `Logins` ON `Verifications`.`badgeNumber` = `Logins`.`badgeNum`

And

SELECT 'Override' as scan, mrn, ecd, babyName, badgeNumber, verifiedBy, adLogin, 
        ts, reason 
FROM (`overrides`) 
LEFT JOIN `Logins` ON `overrides`.`badgeNumber` = `Logins`.`badgeNum` 

The first query results in 723 records and the second one results in none. but when I union the two queries the number of records is reduced to 714???

Answer 1

请尝试使用 UNION ALL。UNION 会删除重复记录，而 UNION ALL 也会保留重复记录。