Creating an update trigger is causing an error - sql

Question

There are two triggers; the first trigger is running perfectly but I want to add another trigger to the same table.
The second trigger is an after update trigger. Please check and tell my is it right or wrong or if we run this trigger it will run perfect or not
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
ALTER TRIGGER [dbo].[tr_issueBook]
ON [dbo].[IssueBooks]
FOR INSERT
AS
BEGIN
DECLARE #IsbnNumber varchar(255)
SELECT #IsbnNumber = ISBN_Number FROM inserted
UPDATE searchBooks
SET tbl_numberOfCopies = tbl_numberOfCopies - 1
WHERE tbl_IsbnBooks = #IsbnNumber
END
/******2nd Trigger ******/
CREATE TRIGGER [dbo].[tr_issueBook2]
ON [dbo].[IssueBooks]
AFTER UPDATE
AS
BEGIN
DECLARE #IsbnNumber varchar(255)
SELECT #IsbnNumber = BookTitle FROM updated
UPDATE searchBooks
SET tbl_numberOfCopies = [tbl_numberOfCopies] + 1
WHERE tbl_bookTitle = #IsbnNumber
END
My second trigger is throwing an error:
invalid object name updated

Answer 1

Both of your triggers are currently broken because you do not handle the case when the Inserted pseudo table has more or less rows than 1. You need to treat the Inserted pseudo table like you would any other table and perform set based operations on it instead of procedural logic.
-- INSERT Trigger - using the Inserted pseudo table
update searchBooks set
tbl_numberOfCopies = tbl_numberOfCopies - 1
where tbl_IsbnBooks in (select ISBN_Number from Inserted);
-- UPDATE Trigger - also using the Inserted pseudo table (There is no Updated table)
update searchBooks set
tbl_numberOfCopies = tbl_numberOfCopies + 1
where tbl_IsbnBooks in (select ISBN_Number from Inserted);
I highly recommend reading the Official Documentation.