This article explains the role of Triggers in SQL Server database, while also addressing the right way to use them in the database management system.
Triggers are a type of advanced storage procedure, which are written to perform actions in a table like UPDATE, DELETE or INSERT. Users often make the mistake of overusing Triggers which is the leading cause for issues in their system’s performance. It is very essential for the users to properly use Triggers, or they could end up losing their precious data.
What are Triggers?
Triggers are used for performing auditing actions, which helps in maintaining table integrity for native constraints like check constraints and foreign key or for performing processing tasks in other posts like DML.
How Triggers Work?
When triggers are fired in a database, they go to the selected table and modify or audit the data that the users enter to change. Triggers are stored in virtual tables which consist of all the data before as well as after the modification. These tables are referred to as deleted and inserted. Whenever working with these tables users should ensure to work on them as a set. These tables basically record all the changes implemented by the user on the SQL database.
How and when they are used?
Triggers are operated under the scope of any sort of transaction in the database, so if a user were to update his/her table he/she would have to use Trigger in order to run the update command.
Note that the change in the auditing action will only be reflected, when the trigger is completed. In case the user is using multiple triggers at a time, the SQL server will lock download the database until all the pending triggers are completed.
Points to Keep in Mind while Working with Triggers
- Users should note that triggers are responsible for extending the life of the transactions, so if you run multiple triggers at a time, the system will automatically lock the server which will prevent you from using any command.
- Triggers can be very stealthy, which often make troubleshooting data problems more tedious and difficult.
- Using Triggers for accomplishing common integrity can be a bad idea; they work on an extended transaction life.
- Note that in case of integrity violation during a trigger transaction, the database can be prone to a potential risk of data damage. So make sure to wait for the system during these ROLLBACK of data modification else you might end up losing it all.
- Users can use Native constraints in such situations as they are less likely to cause a ROLLBACK during any modification, even if there is any violation.
Common Trigger Code Mistakes
Usually while working with Triggers users often use its command to reflect changes in a single row. They assume trigger to work one by one, modifying a single row and then moving to the next row. Well fortunately, this is a false assumption and triggers can be used for multiple rows and columns at a time.
We recommend users to minimize the tasks by specifying the code, to avoid any troubleshooting data issues, because they can be a real pain to resolve. In case you notice data errors, always opt for an mdf recovery tool to avoid any data loss scenario.
Victor Simon is a data recovery expert in DataNumen, Inc., which is the world leader in data recovery technologies, including repair Access and sql recovery software products. For more information visit https://www.datanumen.com/