WHAT IS functions and triggers in SQL?
PL/pgSQL can be used to define trigger functions on data changes or database events. A trigger function is created with the CREATE FUNCTION command, declaring it as a function with no arguments and a return type of trigger (for data change triggers) or event_trigger (for database event triggers).
What is a trigger in PL SQL?
A PL/SQL trigger is a named database object that encapsulates and defines a set of actions that are to be performed in response to an insert, update, or delete operation against a table. Triggers are created using the PL/SQL CREATE TRIGGER statement.
What is trigger and its types?
A trigger defines a set of actions that are performed in response to an insert, update, or delete operation on a specified table. When such an SQL operation is executed, the trigger is said to have been activated. Triggers are optional and are defined using the CREATE TRIGGER statement.
What are the functions in PL SQL?
A stored function (also called a user function or user-defined function) is a set of PL/SQL statements you can call by name. Stored functions are very similar to procedures, except that a function returns a value to the environment in which it is called. User functions can be used as part of a SQL expression.
What is trigger with example?
Trigger: A trigger is a stored procedure in database which automatically invokes whenever a special event in the database occurs. For example, a trigger can be invoked when a row is inserted into a specified table or when certain table columns are being updated.
What is trigger explain?
A trigger is a block of code that is executed automatically from a database statement. Triggers is generally executed for DML statements such as INSERT, UPDATE or DELETE. It resides in a database code and is fired automatically when the database code requires to perform the INSERT ,UPDATE or DELETE statement.
What is trigger and its advantages?
Advantages of Triggers
Enforces referential integrity. Event logging and storing information on table access. Auditing. Synchronous replication of tables. Imposing security authorizations.
How many types of triggers exist in PL SQL?
Answer: There are two types of triggers in PL/SQL. They are Row-level trigger and Statement-level trigger.
What is trigger in PL SQL with examples?
Triggers are stored programs, which are automatically executed or fired when some events occur. Triggers are, in fact, written to be executed in response to any of the following events − A database manipulation (DML) statement (DELETE, INSERT, or UPDATE) A database definition (DDL) statement (CREATE, ALTER, or DROP).
What are the two types of triggers?
There are two types of triggers.
- BEFORE trigger: – This trigger is called before the execution of the DML statement. …
- After Trigger: – this trigger is called after once DML statement is executed. …
- Combination of triggers: – We can have combination of row, statement, BEFORE and AFTER triggers.
What are different triggers?
In SQL Server we can create four types of triggers Data Definition Language (DDL) triggers, Data Manipulation Language (DML) triggers, CLR triggers, and Logon triggers.
What is difference between stored procedure and function?
The function must return a value but in Stored Procedure it is optional. Even a procedure can return zero or n values. Functions can have only input parameters for it whereas Procedures can have input or output parameters. Functions can be called from Procedure whereas Procedures cannot be called from a Function.
Is Vs as in PL SQL?
Question: What is the difference between ‘IS’ and ‘AS’ in PL/SQL? Answer: The PL/SQL language evolved such the the “IS” and “AS” operators are equivalent. Functionally the “IS” and “AS” syntax performs identical functions and can be used interchangeably.
What is the difference between PL SQL procedure and function?
Procedure Vs. Function: Key Differences
|Used mainly to a execute certain process||Used mainly to perform some calculation|
|Cannot call in SELECT statement||A Function that contains no DML statements can be called in SELECT statement|
|Use OUT parameter to return the value||Use RETURN to return the value|