Difference between Stored Procedure and Function in SQL

In SQL, Stored Procedures and Functions are both used to encapsulate reusable logic, but they serve different purposes and have key differences in how they are used, structured, and executed. Understanding these differences is essential for designing efficient and maintainable database systems.

What is a Stored Procedure?

A Stored Procedure is a precompiled collection of one or more SQL statements that perform a specific task. It can accept input parameters, perform operations such as INSERT, UPDATE, DELETE, and SELECT, and can also return output parameters or a result set.

Key Features of Stored Procedures:

• Can perform DML (Data Manipulation Language) operations.

• Can return multiple values via output parameters.

• Can call other procedures and functions.

• Can handle exceptions using TRY...CATCH.

• Execution does not return a value directly (unless using output parameters).

What is a Function?

A Function in SQL is a database object that accepts parameters, performs actions (usually calculations or transformations), and returns a single value. Unlike stored procedures, functions must return a value.

Key Features of Functions:

• Must return a value (scalar or table).

• Cannot perform INSERT, UPDATE, DELETE operations (in most DBMS).

• Cannot use transactions (COMMIT/ROLLBACK).

• Cannot call procedures but can call other functions.

• Primarily used for computations and data transformation.
  
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