Here is a simple PL/pgSQL function that checks the availability of a book by its ISBN. This function assumes that there is another table `Copies` that keeps track of each copy of a book and whether it is available or not.

```sql
CREATE OR REPLACE FUNCTION check_availability(isbn VARCHAR)
RETURNS INTEGER AS $$
DECLARE
available INTEGER;
BEGIN
SELECT COUNT(*)
INTO available
FROM Copies
WHERE books_isbn = isbn AND is_available = TRUE;

IF available 0 THEN
RETURN 1;
ELSE
RETURN 0;
END IF;
END; $$
LANGUAGE plpgsql;
```

You can use this function to check the availability of the book with ISBN 9780451524935 like this:

```sql
SELECT check_availability('9780451524935');
```

This will return 1 if the book is available and 0 if it is not.

Please note that this is a very basic implementation and might need to be adjusted based on the actual structure and requirements of your database.

Question

Here is a simple PL/pgSQL function that checks the availability of a book by its ISBN. This function assumes that there is another table `Copies` that keeps track of each copy of a book and whether it is available or not.

```sql
CREATE OR REPLACE FUNCTION check_availability(isbn VARCHAR)
RETURNS INTEGER AS $$
DECLARE
    available INTEGER;
BEGIN
    SELECT COUNT(*)
    INTO available
    FROM Copies
    WHERE books_isbn = isbn AND is_available = TRUE;

IF available > 0 THEN
        RETURN 1;
    ELSE
        RETURN 0;
    END IF;
END; $$
LANGUAGE plpgsql;
```

You can use this function to check the availability of the book with ISBN 9780451524935 like this:

```sql
SELECT check_availability('9780451524935');
```

This will return 1 if the book is available and 0 if it is not.

Please note that this is a very basic implementation and might need to be adjusted based on the actual structure and requirements of your database.

Knowee AI · Accepted Answer

Here is a simple PL/pgSQL function that checks the availability of a book by its ISBN. This function assumes that there is another table `Copies` that keeps track of each copy of a book and whether it is available or not.

```sql
CREATE OR REPLACE FUNCTION check_availability(isbn VARCHAR)
RETURNS INTEGER AS $$
DECLARE
    available INTEGER;
BEGIN
    SELECT COUNT(*)
    INTO available
    FROM Copies
    WHERE books_isbn = isbn AND is_available = TRUE;

IF available > 0 THEN
        RETURN 1;
    ELSE
        RETURN 0;
    END IF;
END; $$
LANGUAGE plpgsql;
```

You can use this function to check the availability of the book with ISBN 9780451524935 like this:

```sql
SELECT check_availability('9780451524935');
```

This will return 1 if the book is available and 0 if it is not.

Please note that this is a very basic implementation and might need to be adjusted based on the actual structure and requirements of your database.

Question

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