What is the Difference Between Stored Procedure and Function?

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The main differences between stored procedures and functions in SQL are as follows:

  • Return Type: A function has a return type and returns a value, while a procedure does not have a return type but can return values using OUT parameters.
  • Data Manipulation Queries: You cannot use a function with Data Manipulation Language (DML) queries like INSERT, UPDATE, or DELETE. Only SELECT queries are allowed in functions. In contrast, you can use DML queries with procedures.
  • Parameters: Functions can only have input parameters, whereas procedures can have both input and output parameters.
  • Transaction Management: You cannot manage transactions inside a function, while you can manage transactions inside a procedure.
  • Calling: You cannot call stored procedures from a function, but you can call a function from a stored procedure. You can call a function using a SELECT statement, but you cannot call a procedure using SELECT statements.

In summary, stored procedures are more flexible and can perform a wider range of tasks, including DML operations and transaction management. They can also accept both input and output parameters, making them more versatile than functions. Functions, on the other hand, are more limited in their capabilities and are primarily used for calculations and retrieving values based on input parameters.

Comparative Table: Stored Procedure vs Function

Here is a table comparing the differences between stored procedures and functions:

Feature Stored Procedures Functions
Return Type Optional Mandatory
Parameters Input and Output Input only
Data Manipulation Allowed (SELECT, INSERT, UPDATE, DELETE) Allowed only for SELECT queries
Output Parameters Allowed Not Allowed
Transactions Can manage Cannot manage
Calling Can call functions Can be called from SELECT statements
Reusability Less flexible More flexible

Stored procedures are pre-compiled objects that can have both input and output parameters, and they can perform data manipulation tasks such as SELECT, INSERT, UPDATE, and DELETE. Functions, on the other hand, can only have input parameters, and they must return a value. Functions can be used in SELECT statements, while stored procedures cannot. Stored procedures can manage transactions, while functions cannot. Additionally, functions can be called from stored procedures, but stored procedures cannot be called from functions.