Whenever a row is delete in the Customers Table, the following trigger will be executed. The following Trigger is fetching the CustomerId of the deleted record and the fetched value is inserted in the CustomerLogs table. The following screenshot displays the Log table after the above Triggers were executed.
Instead Of Triggers. Below is an example of an Instead Of Delete Trigger. Whenever anyone tries to delete a row from the Customers table the following trigger is executed. Inside the Trigger, I have added a condition that if record has CustomerId value 2 then such a record must not be deleted and an error must be raised.
Also a record is inserted in the CustomerLogs table. If the CustomerId value is not 2 then a delete query is executed which deletes the record permanently and a record is inserted in the CustomerLogs table.
The following error message shown when record with CustomerId 2 is deleted. The following screenshot displays the Log table after the Instead Of Trigger is executed. Related Articles. Add Comments. Thank you for the feedback. The comment is now awaiting moderation. MyTrigger ON dbo.
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View all my tips. In these cases, the Inserted and Deleted recordsets will be empty. In many cases, if both the Inserted and Deleted recordsets are empty you might just want to exit the trigger without doing anything.
Since not all columns can be updated at a time you can check whether a particular column is being updated by something like this:. I like solutions that are "computer science elegant. It does make the assumption that it does not matter what the DML statement was if no rows were modified which should satisfy the vast majority of cases. So while it is not as complete as Roman Pekar's solution, it is more efficient. Obviously, every implementation model has its pros and cons; you will need to evaluate your systems individually for what really works best.
And vice versa. I know it's quick and maybe dirty. And it's an old post. But, hey, I was searching for a solution a for long time, and maybe somebody finds my way somewhat useful anyway. All the best! So after researching this topic a little bit I've found more precise solution:. I've used a bit complex way of calculating see helpful article below. Also, this approach will still incorrectly classifies some updates as inserts if every column in the table is affected by update , and probably it will classifies inserts where there only default values are inserted as deletes, but those are king of rare operations at lease in my system they are.
Besides that, I don't know how to improve this solution at the moment. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. Insert Update trigger how to determine if insert or update Ask Question. Asked 12 years, 9 months ago. Active 1 year, 6 months ago. Viewed k times. Improve this question. Add a comment.
Indicates that the trigger shouldn't be run when a replication agent modifies the table that's involved in the trigger. Trigger conditions specify additional criteria that determine whether the tried DML, DDL, or logon events cause the trigger actions to be run. The trigger actions specified in the Transact-SQL statements go into effect when the operation is tried. Triggers can include any number and type of Transact-SQL statements, with exceptions. For more information, see Remarks.
A trigger is designed to check or change data based on a data modification or definition statement; it should't return data to the user. The Transact-SQL statements in a trigger frequently include control-of-flow language. DML triggers use the deleted and inserted logical conceptual tables. They're structurally similar to the table on which the trigger is defined, that is, the table on which the user action is tried.
The deleted and inserted tables hold the old values or new values of the rows that may be changed by the user action. For example, to retrieve all values in the deleted table, use:. For more information, see Use the inserted and deleted Tables. Avoid using these data types in new development work, and plan to modify applications that currently use them. Use nvarchar max , varchar max , and varbinary max instead. For a CLR trigger, specifies the method of an assembly to bind with the trigger.
The method must take no arguments and return void. If the class has a namespace-qualified name that uses '. The class can't be a nested class. DML triggers are frequently used for enforcing business rules and data integrity. However, DRI doesn't provide cross-database referential integrity.
Referential integrity refers to the rules about the relationships between the primary and foreign keys of tables. This successful execution includes all referential cascade actions and constraint checks associated with the object updated or deleted.
Instead, the statement is resolved as modifications against the base tables underlying the view. In this case, the view definition must meet all the restrictions for an updatable view. For a definition of updatable views, see Modify Data Through a View. Each modification to an underlying base table starts the chain of applying constraints and firing AFTER triggers defined for the table.
This function returns a bit pattern that indicates which columns were inserted or updated. A trigger is created only in the current database; however, a trigger can reference objects outside the current database. If the trigger schema name is specified to qualify the trigger, qualify the table name in the same way.
Any SET statement can be specified inside a trigger. The SET option selected remains in effect during the execution of the trigger and then reverts to its former setting. When a trigger fires, results are returned to the calling application, just like with stored procedures.
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