I am creating a book tracking database for myself that holds information about my books and allows me to keep track of who is borrowing them. I am trying to create a trigger on my Checkouts table that runs if a record is added or updated that will determine if a checkout data has been entered or if a checkin date has been entered and change the "available" field in my Books table to "Y" or "N".
I have created a trigger called "update_book_availablility" on my Checkouts table but I keep getting this error:
"PLS-00103: Encountered the symbol 'end-of-file' when expecting one of the following: ( begin case declare and exception exit for goto if loop mod null pragma raise return select update while with <<continue close current delete fetch lock insert open rollback savepoint set sql execute commit forall merge standard pipe purge json_object
Errors: check compiler log"
Here is my trigger code:
CREATE OR REPLACE NONEDITIONABLE TRIGGER "UPDATE_BOOK_AVAILABILITY"
AFTER INSERT OR UPDATE OF ISBN, PersonID, checkout_date, checkin_date
ON Checkouts
FOR EACH ROW
BEGIN
IF :NEW.checkout_date = NULL
THEN
UPDATE Book
SET available = 'N'
WHERE ISBN IN (SELECT :NEW.ISBN FROM Checkouts);
END IF;
END;
Here is an image of my ERD:
ERD
I have been looking into and double checking my trigger syntax, If condition syntax, subquery syntax, and googling this error but have found nothing that has helped. I am new to PL/SQL and would appreciate any help in understanding what I have done wrong or missed.
PLS-00103: Encountered the symbol end-of-file error is SYNTAX ERROR
Copied your trigger and adjusted it to one of my test tables - it works. I removed NONEDITIONABLE and changed trigger table name as well as column names and table/column beeing updated by trigger.
To Do:
Check your syntax again or write the trigger from scratch once more
"...WHERE ISBN IN (SELECT :NEW.ISBN FROM Checkouts)..." selects one fixed value (FOR EACH ROW) :NEW.ISBN of triggering table, better ->> "... WHERE ISBN = :NEW.ISBN ..."
Prety sure that you don't need NONEDITIONABLE trigger for your books tracking app...
Regards...
before inserting in the table i am validating if the ID already exists in table.
It does not exists. Even though it through this error. Is there any possibility that the table does not allow to insert may be permission issue.
I have that insert query in a procedure, is there a possibility that due to procedure permission it doesn't allow.
If you check in the first statement/transaction for existences and you run this SP in parallel it is possible that the second (INSERT) statement/transaction fails.
In this case you can use a MERGE statement which either inserts the data or updates on existences in one transaction.
I have a simple, single table sqlite3 database file that has exactly one table. There are no keys, foreign or domestic. There are no triggers. I have the following workflow:
If the database file exixts open it.
Start exclusive transaction
Select all rows from the table in order.
Operate on each row.
Delete each operated-on row.
When done, count the number of remaining rows in the table, if 0 then DROP the table then unlink the database file
Commit or Rollback the transaction
The drop-table always fails with the message that the table is locked. I've seen a couple of other posts that suggest that there could be open statement handles or other cruft lying around. Since I am using "sqlite_exec()"s for all of this I do not have any open DB anything except the DB handle itself.
Is drop table not allowed in transactions?
When dropping a table, you get the "table is locked" message when there is still some active cursor on the table, i.e., when you did not finalize a statement (or did not close a query object in whatever language you're using).
Suppose I have a user table that creates strong relationships (Enforce Foreign Key Constraint) with many additional tables. Such orders table ..
If we try to delete a user with some orders then SqlException will arise.. How can I catch this exception and treat it properly?
Is this strategy at all?
1) first try the delete action if an exception Occur handel it?
2) Or maybe before the delete action using code adapted to ensure that offspring records throughout the database and alert according to .. This piece of work ...
So how to do it?
--Edit:
The goal is not to delete the records from the db! the goal is to inform the user that this record has referencing records. do i need to let sql to execute the delete command and try to catch SqlException? And if so, how to detect that is REFERENCE constraint SqlException?
Or - should I need to write some code that will detect if there are referencing records before the delete command. The last approach give me more but its a lot of pain to implement this kind of verification to each entity..
Thanks
Do you even really want to actually delete User records? Instead I'd suggest having a "deleted" flag in your database, so when you "delete" a user through the UI, all it does is update that record to set the flag to 1. After all, you wouldn't want to delete users that had orders etc.
Then, you just need to support this flag in the appropriate areas (i.e. don't show "deleted" users in the UI).
Edit:
"...but just for the concept, assume that i do want delete the user how do i do that?"
You'd need to delete the records from the other tables that reference that user first, before deleting the user record (i.e. delete the referencing records first then delete the referenced records). But to me that doesn't make sense as you would be deleting e.g. order data.
Edit 2:
"And if so, how to detect that is REFERENCE constraint SqlException?"
To detect this specific error, you can just check the SqlException.Number - I think for this error, you need to check for 547 (this is the error number on SQL 2005). Alternatively, if using SQL 2005 and above, you could handle this error entirely within SQL using the TRY...CATCH support:
BEGIN TRY
DELETE FROM User WHERE UserId = #MyUserId
END TRY
BEGIN CATCH
IF (ERROR_NUMBER() = 547)
BEGIN
-- Foreign key constraint violation. Handle as you wish
END
END CATCH
However, I'd personally perform a pre-check like you suggested though, to save the exception. It's easily done using an EXISTS check like this:
IF NOT EXISTS(SELECT * FROM [Orders] WHERE UserId=#YourUserId)
BEGIN
-- User is not referenced
END
If there are more tables that reference a User, then you'd need to also include those in the check.
I would like to find out if it is possible to find out which package or procedure in a package is updating a table?
Due to a certain project being handed over (the person who handed over the project has since left) without proper documentation, data that we know we have updated always go back to some strange source point.
We are guessing that this could be a database job or scheduler that is running the update command without our knowledge. I am hoping that there is a way to find out where the source code is calling from that is updating the table and inserting the source as a trigger on that table that we are monitoring.
Any ideas?
Thanks.
UPDATE: I poked around and found out
how to trace a statement back to its
owning PL/SQL object.
In combination with what Tony mentioned, you can create a logging table and a trigger that looks like this:
CREATE TABLE statement_tracker
( SID NUMBER
, serial# NUMBER
, date_run DATE
, program VARCHAR2(48) null
, module VARCHAR2(48) null
, machine VARCHAR2(64) null
, osuser VARCHAR2(30) null
, sql_text CLOB null
, program_id number
);
CREATE OR REPLACE TRIGGER smb_t_t
AFTER UPDATE
ON smb_test
BEGIN
INSERT
INTO statement_tracker
SELECT ss.SID
, ss.serial#
, sysdate
, ss.program
, ss.module
, ss.machine
, ss.osuser
, sq.sql_fulltext
, sq.program_id
FROM v$session ss
, v$sql sq
WHERE ss.sql_address = sq.address
AND ss.SID = USERENV('sid');
END;
/
In order for the trigger above to compile, you'll need to grant the owner of the trigger these permissions, when logged in as the SYS user:
grant select on V_$SESSION to <user>;
grant select on V_$SQL to <user>;
You will likely want to protect the insert statement in the trigger with some condition that only makes it log when the the change you're interested in is occurring - on my test server this statement runs rather slowly (1 second), so I wouldn't want to be logging all these updates. Of course, in that case, you'd need to change the trigger to be a row-level one so that you could inspect the :new or :old values. If you are really concerned about the overhead of the select, you can change it to not join against v$sql, and instead just save the SQL_ADDRESS column, then schedule a job with DBMS_JOB to go off and update the sql_text column with a second update statement, thereby offloading the update into another session and not blocking your original update.
Unfortunately, this will only tell you half the story. The statement you're going to see logged is going to be the most proximal statement - in this case, an update - even if the original statement executed by the process that initiated it is a stored procedure. This is where the program_id column comes in. If the update statement is part of a procedure or trigger, program_id will point to the object_id of the code in question - you can resolve it thusly:
SELECT * FROM all_objects where object_id = <program_id>;
In the case when the update statement was executed directly from the client, I don't know what program_id represents, but you wouldn't need it - you'd have the name of the executable in the "program" column of statement_tracker. If the update was executed from an anonymous PL/SQL block, I'm not how to track it back - you'll need to experiment further.
It may be, though, that the osuser/machine/program/module information may be enough to get you pointed in the right direction.
If it is a scheduled database job then you can find out what scheduled database jobs exist and look into what they do. Other things you can do are:
look at the dependencies views e.g. ALL_DEPENDENCIES to see what packages/triggers etc. use that table. Depending on the size of your system that may return a lot of objects to trawl through.
Search all the database source code for references to the table like this:
select distinct type, name
from all_source
where lower(text) like lower('%mytable%');
Again that may return a lot of objects, and of course there will be some "false positives" where the search string appears but isn't actually a reference to that table. You could even try something more specific like:
select distinct type, name
from all_source
where lower(text) like lower('%insert into mytable%');
but of course that would miss cases where the command was formatted differently.
Additionally, could there be SQL scripts being run through "cron" jobs on the server?
Just write an "after update" trigger and, in this trigger, log the results of "DBMS_UTILITY.FORMAT_CALL_STACK" in a dedicated table.
The purpose of this function is exactly to give you the complete call stack of al the stored procedures and triggers that have been fired to reach your code.
I am writing from the mobile app, so i can't give you more detailed examples, but if you google for it you'll find many of them.
A quick and dirty option if you're working locally, and are only interested in the first thing that's altering the data, is to throw an error in the trigger instead of logging. That way, you get the usual stack trace and it's a lot less typing and you don't need to create a new table:
AFTER UPDATE ON table_of_interest
BEGIN
RAISE_APPLICATION_ERROR(-20001, 'something changed it');
END;
/