Procedures are widely used in development environments as they work as a kind of methods in the database and its main functions to optimize the processing of complex commands and also reuse code.
In PostgreSQL, the procedures are created using the following syntax:
CREATE OR REPLACE FUNCTION [Procedure Name]
RETURN [Type of return]
In the declaration of a procedure the instructions CREATE and ALTER are used simultaneously so there are no problems as duplicate inclusion, for example, which would cause execution errors.
In PostgreSQL, unlike other DBMS, you must always tell the kind of returns that the procedure will take. The return is the most common setof referred queries in database, this return type is mainly used in the construction of reports as shown below:
CREATE OR REPLACE FUNCTION productList()
RETURN setof vproduct
SELECT Name, Price FROM product
Note that in the above procedure we are listing the field name and price from product table, this information will be returned through the variable declared as vprodutos return.
Importantly, any variable can be returned in a procedure according to the need of implementation.
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