Convert Triggers From PostgreSQL to MS SQL

PostgreSQL is an open-source relational database management system (RDBMS) with a focus on speed and compatibility. Its features include atomicity, consistency, isolation, durability, automatically updatable views, materialized views, triggers, foreign keys, and stored procedures.

It is used by many companies including Apple, Facebook, Etsy, Instagram, Red Hat, Skype, Spotify, and others. It has a professional community that helps you find solutions to your problems.

Triggers in PostgreSQL

Triggers in PostgreSQL are a convenient way to handle table-related events such as INSERT, UPDATE, DELETE and TRUNCATE. They can also be used to enforce business rules and maintain database integrity.

They are classified according to whether they fire before, after, or instead of the operation. BEFORE triggers naturally fire before the statement starts to do anything, while AFTER triggers fire at the end of the statement.

The name must be distinct from the names of other triggers for the same table. It cannot be schema-qualified — the trigger inherits the schema of its table.

A trigger can also be set to fire before or after a table-related event (before constraints are checked and an INSERT, UPDATE or DELETE is attempted on a row); or to fire instead of the event, in the case of inserts, updates or deletes on a view. This option is especially useful in cases of foreign-key enforcement actions.

Triggers in MS SQL

A trigger is a database object that fires automatically whenever certain events happen in the database. These events can be anything from an insert, update or delete statement on a table to a user logging into a server instance.

There are two classes of triggers: DDL (data definition language) and DML (data modification language). DDL triggers fire when data is created, changed or deleted.

DML triggers are the most common type and fire when a data modification statement is tried on the specified table or view. They can be used for auditing and enforcing business rules.

INSERT and DELETE triggers are both supported by PostgreSQL. In both cases, the inserted/updated/deleted data is stored in special tables called INSERTED and DELETED.

The OLD and NEW column values of the rows in the INSERTED and DELETED tables can be used as row variables in FOR EACH ROW triggers. However, they are not available in the REFERENCING clause.

Triggers in SSMS

Triggers are a type of database object that automatically invokes whenever certain events occur in the database. This can include inserting or deleting rows, a user logging into a database server instance, updating a table column, and so on.

While triggers are useful, they also come with several pitfalls that can lead to complex and complicated code. Keeping triggers as simple as possible minimizes these problems.

A trigger can be defined on a table and can be associated with a function, stored procedure, or view. The CREATE TRIGGER statement can be used to create a new trigger, or replace an existing trigger.

In addition, triggers can be used to track aggregated columns in a table. This helps to determine how changes affect a given row.

Lastly, triggers can be used to maintain complex business logic. In general, this type of functionality is best implemented in an application.

Triggers in PgAdmin

Triggers are a useful way to enforce business rules, validate input data and keep an audit trail. They are used in many databases to speed application development and make it easier to change business policies without changing each database application program.

To create a trigger in PostgreSQL, first define a function that is bound to a table or view. You can use a FOR EACH ROW clause or a FOR EACH STATEMENT clause to specify the time in which the trigger is fired.

Suppose that we want to add a trigger to the employee table that will log the changes in the last_name column when an employee’s last name changes. We can do this by using the CREATE TRIGGER command.

Specify the name of the trigger after the ON keyword and a few other details such as the timing that cause it to fire and the name of the table associated with it. We can also optionally specify the CONSTRAINT option, which allows us to set constraints on the trigger.


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