Table name variable in MS SQL query - sql

Question

I have dynamically created tables, like XXX_JOURNAL.
Where XXX - is table prefix (variable), and _JOURNAL - is constant in table name.
I need create UPDATE trigger on database, not on particular table, and use table name (prefix) as variable:
CREATE TRIGGER triggerName ON %_JOURNAL
FOR UPDATE
AS
UPDATE XXX_JOURNAL
SET COMPANY_ID = LEFT(tableName,3) //tableName = current table (XXX_JOURNAL)
WHERE ID = ID FROM inserted
So here I have two difficulties:
How to create one trigger for all tables LIKE %_JOURNAL?
How to use table name as the keyword for current table?
I know there are a lot of mistakes in syntax. For example, I cannot use '%_JOURNAL' as table name on trigger creation. It's just for explanation, that I need create one trigger for all dynamically created tables in future.
Any ideas?

Answer 1

You can use stored procedure with dynamic SQL:
CREATE PROCEDURE TriggerCreationForJournals
#XXX as nvarchar(3)
AS
BEGIN
DECLARE #sql nvarchar(max),
#triggerName nvarchar(max) = #XXX + N'_JOURNAL_UPDATE',
#objectCheck int,
#checkSQL nvarchar(max),
#params nvarchar(max) = N'#objectCheck int OUTPUT'
SELECT #checkSQL = N'SELECT #objectCheck = OBJECT_ID(N'''+#triggerName+''')'
EXEC sp_executesql #checkSQL, #params, #objectCheck = #objectCheck OUTPUT
IF #objectCheck IS NULL
BEGIN
SELECT #sql = N'
CREATE TRIGGER '+QUOTENAME(#triggerName)+' ON ['+#XXX+'_JOURNAL]
FOR UPDATE
AS
UPDATE x
SET COMPANY_ID = '''+#XXX+'''
FROM ['+#XXX+'_JOURNAL] x
INNER JOIN inserted i
ON i.ID = x.ID'
EXEC sp_executesql #sql
END
ELSE
BEGIN
PRINT 'Trigger '+QUOTENAME(#triggerName)+' already exists'
END
END
Then run this:
DECLARE #sql nvarchar(max)
SELECT #sql = (
SELECT 'EXEC TriggerCreationForJournals '''+LEFT([name],3) +''';' +CHAR(10)
FROM sys.tables
WHERE [name] LIKE '%JOURNAL'
FOR XML PATH('')
)
EXEC sp_executesql #sql
To create triggers for all tables.
In #sql there will be query like:
EXEC TriggerCreationForJournals 'AFG';
EXEC TriggerCreationForJournals 'DFG';
The purpose of stored procedure is to check if trigger on table exists - if so skip its creation, you can modify the SP to drop them if exists.
The second part is a creation of script and running the SP for all tables you need.
Hope, this answer helps you with your questions.