Verwenden mehrerer verschachtelter Abfragen in Oracle DBMS

Ihre Anfrage:

SELECT Email, Phonenumber
FROM EMPLOYEE
WHERE COUNT(
ID = (SELECT ID_Num
FROM SCHEDULE
WHERE Start_Time <= 12:07 AND End_Time >= 12:07)
AND Shopn = (SELECT Shopname
FROM SHOP
WHERE Shoptype = ‘market’) ) > 2

Probleme :

1. Es scheint, dass Sie versuchen, die ID mit dem Operator "=" auszuwählen, was fehlschlägt, wenn mehrere Einträge von der inneren Abfrage zurückgegeben werden.
2. Sie können in der where-Klausel keine Aggregatoperatoren hinzufügen.

Mögliche Antwort:

select Email, Phonenumber
FROM EMPLOYEE
WHERE ID in (SELECT ID_Num
FROM SCHEDULE
WHERE Start_Time <= '12:07' AND End_Time >= '12:07')
AND Shopn in (SELECT Shopname
FROM SHOP
WHERE Shoptype = 'market')
and (  
select count(distinct id)
FROM EMPLOYEE
WHERE ID in (SELECT ID_Num
FROM SCHEDULE
WHERE Start_Time <= '12:07' AND End_Time >= '12:07')
AND Shopn in (SELECT Shopname
FROM SHOP
WHERE Shoptype = 'market')) > 2;