Implementing stored procedures, user-defined functions, triggers
Stored procedures
Stored procedures are linear or sequential programs.
Stored procedures can accept parameters and allow local variable declarations; they are structured and allow the use of submodules; also, they allow repeated and conditional statement execution.
Create
CREATE PROC[EDURE] <procedure_name>
[@<parameter_name> <datatype> [= <default>] [OUTPUT] ], ...
AS
<procedure_body>
Remove
DROP PROCEDURE [qualifier.]<procedure_name>
User-defined Functions
User-defined functions combine the advantages of stored procedures with the capabilities of SQL predefined functions. They can accept parameters, perform specific calculations based on data retrieved by one or more SELECT statement, and return results directly to the calling SQL statement.
Create
CREATE FUNCTION <function_name>
([@<parameter_name> <datatype> [ = <default>]],...)
RETURNS <datatype>
[AS]
BEGIN
<function_body>
RETURN <value>
END
Remove
DROP FUNCTION [qualifier.]<function_name>
Triggers
A trigger is a special type of stored procedure that fires off automatically 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.
Create
CREATE TRIGGER <trigger_name>
ON <table_or_view>
{ FOR | AFTER | INSTEAD OF }
{INSERT | UPDATE | DELETE}
AS
[IF UPDATE ( <column_name> )
[AND | OR UPDATE ( <column_name> ) ],...]
<trigger_body>
Remove
DROP TRIGGER [qualifier.]<trigger_name>
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