What are SQL Stored Procedure and Function

In database management and application development processes, the concepts of SQL Stored Procedure and Function play an important role in terms of code reusability, security, and maintenance. These two structures allow us to manage complex operations on the database side and increase performance thanks to optimized query engines. Especially in large and complex projects, they are frequently used to perform operations on the database in a more organized and secure way.

What is an SQL Stored Procedure?

A Stored Procedure is a set of procedures stored in the database that bring together one or more SQL commands to complete a specific task. Users or applications can call this procedure when needed to perform operations collectively, repeatedly, and reliably.

Example of Creating a Stored Procedure

CREATE PROCEDURE sp_KullaniciListele
AS
BEGIN
    SELECT * FROM Kullanicilar;
END;

With the example above, for those who wonder what SQL Stored Procedure is, we can show that more than one query can be run with a single command and a reusable structure can be created.

What is an SQL Function?

An SQL Function is a code block that can take one or more parameters, generally returns a value, and is stored in the database. They are mostly used in mathematical, textual or date calculations, and data manipulation. Functions make code more understandable, easier to maintain, and secure.

Example of Creating an SQL Function

CREATE FUNCTION fn_KdvHesapla (@Tutar DECIMAL(18,2))
RETURNS DECIMAL(18,2)
AS
BEGIN
    RETURN @Tutar * 1.20
END;

The example function here adds 20% VAT to an amount and returns the result. With the use of SQL Function, complex calculations can be performed in one line and securely.

Differences between Stored Procedure and Function

Feature	Stored Procedure	Function
Returns a Value	Optional (can return multiple results)	Always returns a value
How to Call	With EXEC command	With SELECT or another query
Usage Area	Data updating, deleting, inserting, etc.	Computation and value generation

Conclusion

The concepts of SQL Stored Procedure and Function are indispensable components of modern database applications. To centrally manage business rules, optimize repetitive operations, and reduce maintenance costs of code, both procedures and functions should be used effectively. In a well-designed database, it is possible to benefit from the advantages of these structures in the best way.