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Dec 14, 2022 · SQL | Triggers. Trigger is a statement that a system executes automatically when there is any modification to the database. In a trigger, we first specify when the trigger is to be executed and then the action to be performed when the trigger executes. Triggers are used to specify certain integrity constraints and referential constraints that ...
Aug 5, 2023 · Database triggers are types of stored procedures that run in response to an event occurring in a database. They are typically associated with changes made to a table's data, like insertions, updates, or deletions. Triggers are useful for maintaining the data integrity in the database. They can adjust the entire database systematically whenever ...
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- How to Create A Trigger
- How to Drop A Trigger
- When to Use Triggers
- Summary
To create a new trigger, use the CREATE TRIGGERcommand. This command has the following structure: So here's a breakdown of every line: 1. The keyword CREATE TRIGGERis mandatory and is followed by the name of the trigger. You'll use this name to refer to the trigger in future, and to delete the trigger if the need ever arises. This name should be un...
After creating a trigger, you might want to stop its execution for some reason. In this case, you can drop the trigger. To drop the trigger, use the DROP TRIGGERcommand. The command only requires the name of the trigger. You can use the command like this: Running this query will remove the trigger that we created above and every record inserted fro...
Logging: You can have a trigger to automatically write to another table on insertion, update, or deletion of record from a table.Data validation: You can write a trigger to ensure data is a certain type and correct values can be set when needed.Data syncronisation: You can use a trigger to keep related tables updated. For example, in an ecommerce table, every time a sales record gets created, a trigger can update the vendor's balance. Or...I hope you now understand SQL triggers and when to use them so you can write better queries. If you have any questions or relevant advice, please get in touch with me to share them. To read more of my articles or follow my work, you can connect with me on LinkedIn, Twitter, and Github. It’s quick, it’s easy, and it’s free!
Database trigger. A database trigger is procedural code that is automatically executed in response to certain events on a particular table or view in a database. The trigger is mostly used for maintaining the integrity of the information on the database. For example, when a new record (representing a new worker) is added to the employees table ...
Mar 10, 2023 · An SQL trigger allows you to specify SQL actions that should be executed automatically when a specific event occurs in the database. For example, you can use a trigger to automatically update a record in one table whenever a record is inserted into another table. In this article, you will learn what SQL triggers are, how they work, and how to ...
Non-DML triggers, also known as event and system triggers, are can be split into two categories: DDL events and database events. The syntax for both are similar, with the full syntax shown here and a summarized version below. CREATE [OR REPLACE] TRIGGER trigger-name. { BEFORE | AFTER } event [OR event]...
Aug 23, 2023 · CREATE TRIGGER trigger_name – It is used to construct a trigger or to change the name of an existing trigger. BEFORE/AFTER – This query is used to define the trigger’s execution time ( before or after a certain event). INSERT/UPDATE/DELETE – This describes the action we wish to take on the tables.
