Database Triggers

One more post about SQL Tips and Tricks that i think that have is own value. Today I write about Database Triggers, they are used for security reasons and audit operations, let's see the example.

Use Example_DB
go
Create TRIGGER [DBTRG_Test_Drop_Create]
ON DATABASE
FOR DDL_TABLE_VIEW_EVENTS
AS
DECLARE @data xml
DECLARE @cmd nvarchar(350)
DECLARE @logMsg nvarchar(400)

SET @data = eventdata()
SET @cmd = @data.value
('(/EVENT_INSTANCE/TSQLCommand/CommandText)[1]', 'nvarchar(350)')
SET @logMsg = @cmd + ' (' + SYSTEM_USER + ' on ' + HOST_NAME() + ')'

RAISERROR (@logMsg, 10, 1) WITH LOG

-- To visualize the command uncomment the line bellow
-- select @cmd

-- Here we don't allow command that begin with "Create"
-- if the condition is true we do rollback

if left(@cmd,6)='Create'
rollback

-- Here we don't allow command that begin with "Drop"
-- if the condition is true we do rollback

if left(@cmd,4)='drop'
rollback

Note: We can create a table with type specified in variables and insert the attemps of create and drop objects.

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