CODEWITHSUNDEEP
sqloracle-databasetriggers
Kolt Penny
Kolt Penny

Reputation: 164

Is the BEFORE Trigger statement executed before the DDL statement?

Is the BEFORE trigger statement executed before DDL statements or is it inside a DDL statement?

I'm building a small DBMS and currently developing the DDL, and I'm confused about handling the BEFORE statement.

Here's not a defined behaviour for it:

https://web.csulb.edu/colleges/coe/cecs/dbdesign/dbdesign.php?page=sql/ddldml.php

Oracle describes the behaviour but not what can come inside the preceding or following trigger or whether they can be DDL statements or not:

https://www.oracletutorial.com/plsql-tutorial/oracle-trigger/

Upvotes: 0

Views: 1703

Answers (1)

pmdba
pmdba

Reputation: 7033

"BEFORE" is part of the DDL statement that defines the trigger. It describes when the trigger fires in relation to a DML command on a table: i.e. BEFORE or AFTER the change to the data is actually made. This allows you to validate or modify the new data as it is being applied, or to add or modify dependent data like a child table after the parent table update is complete.

While you can technically embed DDL into the body of a trigger using "execute immediate", it is typically considered very bad practice to do so. Is there a specific use case you are considering for including DDL statements in a trigger?

Upvotes: 2

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