SQL Server : update table tries to drop nonexistent triggers - sql

Question

I am using Microsoft SQL Server 2008 R2 (SP2). I am not using SQL Server Management Studio. I am using a simple webpage with a textarea for a query window that I built myself in PHP, so all I am doing are SQL commands -- no GUI stuff. Never had problems with it before, and I don't think the problems I'm having now are because of my PHP. Anyway, I would most appreciate answers in SQL code rather than answers that recommend I right-click the table name in Management Studio, if you get my drift.
Leading up to the problem...
I used to have three triggers on table dbo.MyOldTableName:
trgOldUpdate1, trgOldUpdate2, and trgOldInsert
I renamed the table using the following code:
EXEC sp_rename 'dbo.MyOldTableName', 'MyNewTableName';
I then dropped those three old triggers and created the following three new triggers (which do the same thing but point to the new table and have new names):
trgNewUpdate1, trgNewUpdate2, and trgNewInsert
I ran this SQL and saw only the new triggers:
SELECT
referencing_schema_name,
referencing_entity_name,
referencing_id,
referencing_class_desc,
is_caller_dependent
FROM
sys.dm_sql_referencing_entities ('dbo.MyOldTableName', 'OBJECT');
I ran this SQL and the old triggers are not there:
SELECT * FROM sys.triggers;
Now all of that above information is simply background. Here is the actual problem. I ran a simple update command (like this SQL):
UPDATE [dbo].[MyNewTableName] SET ColumnName = ColumnName;
...and got these error messages:
Cannot drop the trigger 'dbo.trgOldUpdate2', because it does not exist or you do not have permission.
Cannot drop the trigger 'dbo.trgOldUpdate1', because it does not exist or you do not have permission.
Cannot drop the trigger 'dbo.trgOldUpdate1', because it does not exist or you do not have permission.
Cannot drop the trigger 'dbo.trgOldUpdate2', because it does not exist or you do not have permission.
First, why is SQL Server trying to drop triggers on a simple update command (And before you ask, no, the trigger code itself never drops anything at all)?
Second, why is SQL Server looking for triggers that don't exist?
Third and most important, how do I stop this from happening?
Many thanks in advance for your clear, concise, and self-contained answers! (Hey, a guy can dream, can't he?)

Answer 1

My guess is that there was an error in the trigger DROP/CREATE script such that the DROP statements of the old triggers were inadvertently included in in one of the update triggers. Check the new triggers to see if that is the case:
EXEC sp_helptext N'trgNewUpdate1';
EXEC sp_helptext N'trgNewUpdate2';