What is the create trigger statement in PostgreSQL?
The CREATE TRIGGER statement in PostgreSQL implements a subset of the SQL standard. The following functionality is currently missing: SQL allows you to define aliases for the “old” and “new” rows or tables for use in the definition of the triggered action (e.g., CREATE TRIGGER
How to List table triggers in a database?
Query below lists table triggers in a database with their details. There are no comments. Click here to write the first comment.
Which is an example of a trigger function in pgSQL?
Example 42.3 shows an example of a trigger function in PL/pgSQL. Example 42.3. A PL/pgSQL Trigger Function This example trigger ensures that any time a row is inserted or updated in the table, the current user name and time are stamped into the row.
What is the null variable in PostgreSQL trigger function?
Data type RECORD; variable holding the new database row for INSERT / UPDATE operations in row-level triggers. This variable is null in statement-level triggers and for DELETE operations. Data type RECORD; variable holding the old database row for UPDATE / DELETE operations in row-level triggers.
What is the function intersecting ST _ Intersects in PostGIS?
ST_Intersects, Intersects ST_Intersects is a function that takes two geometries and returns true if any part of those geometries is shared between the 2. In PostGIS versions before 1.3 you would use the following syntax to utilize indexes
How many times can a trigger be executed in PostgreSQL?
In contrast, a trigger that is marked FOR EACH STATEMENT only executes once for any given operation, regardless of how many rows it modifies (in particular, an operation that modifies zero rows will still result in the execution of any applicable FOR EACH STATEMENT triggers).
When to return NULL in PostgreSQL trigger function?
Row-level triggers fired BEFORE can return null to signal the trigger manager to skip the rest of the operation for this row (i.e., subsequent triggers are not fired, and the INSERT / UPDATE / DELETE does not occur for this row). If a nonnull value is returned then the operation proceeds with that row value.