SQL Query in Generalization

Question

Relational Schema:

Table comics(Generalization):
    comic_name: varchar(Primary Key)
    Created: boolean(Default = false)
    Group_name: varchar(55), (Not Null)
    Type: varchar(55), (Not Null)

Table Unreleased_comics(Specialization):
    comic_Name: Foreign Key(comics, comic_name)

Table Released_comics(Specialization):
    comic_Name: Foreign Key(comics, comic_name)
    Release_Date: date (Not Null)

Relation in ER: Comics isA Unreleased_Comics and Released_Comics

What should be the SQL Query for listing all the comics that were released before 2001? (MySQL)

The field *Created* doesn't seem to have any use. Do you know what it is? — wallyk, Mar 06 '21 at 20:26
Created field is for status that is the comic is created yet or not @wallyk — Shivam Verma, Mar 06 '21 at 20:27

score 0 · Accepted Answer · answered Mar 06 '21 at 21:23

0

It is a simple INNER JOIN the more colibated part can be to cholse zhe right date, but as you only want the year, is still simple

SELECT 
    c.comic_name, c.Created, c.Group_name, c.Type, r.Release_Date
FROM
    comics crossINNER
        JOIN
    Released_comics r ON c.comic_name = r.comic_name
WHERE
    YEAR(r.Release_Date) < 2001

answered Mar 06 '21 at 21:23

nbk

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the r is actually Released_Comics right?, and c is Comics – Shivam Verma Mar 07 '21 at 06:05

SQL Query in Generalization

1 Answers1