The Difference Between Function and Stored Procedure in SQL
When working with SQL databases, you may come across the terms function and stored procedure. Though both of these are database objects that help with data manipulation, there are some significant differences between the two. In this article, we will discuss the difference between a function and a stored procedure in SQL.
What is a Function?
In SQL, a function is a database object that returns a single value. You can think of it as a formula that takes some input parameters, performs some calculations, and returns a single output value. Functions can be used in SQL queries as expressions – they can be called directly in the SELECT statement, WHERE clause, or even in the ORDER BY clause. There are two types of functions in SQL:
1. Scalar Function: Returns a single value based on input parameters.
2. Table Valued Function: Returns a result set based on input parameters.
What is a Stored Procedure?
A stored procedure is a database object that executes a sequence of statements. Unlike a function, a stored procedure can return multiple result sets or no result set at all. Stored procedures can be used to perform various database operations such as inserting, updating or deleting records, and can also be used to call other stored procedures or functions. Stored procedures are executed using the EXECUTE command.
The Key Differences Between Function and Stored Procedure
1. Return Value: A function returns a single value whereas a stored procedure can return multiple result sets or no result set at all.
2. Usage: Functions are used in SQL queries while stored procedures are used to execute a sequence of statements or perform database operations.
3. Parameters: Functions can have input parameters and return a value based on those parameters. Stored procedures can have input and output parameters that allow them to manipulate data.
4. Portability: Functions are portable – that means they can be easily transferred between databases. Stored procedures, on the other hand, are specific to the database they are created in.
5. Performance: Functions are usually faster than stored procedures as they return a single value. Stored procedures require more processing power as they can return multiple result sets or no result set at all.
Conclusion
In conclusion, functions and stored procedures are two important database objects in SQL that serve different purposes. Functions are used for data manipulation within SQL queries, while stored procedures are used to execute sequences of statements or perform database operations. The key differences between the two are in their return value, usage, parameter handling, portability, and performance. Understanding these differences can help you choose the right tool for your specific database needs.
Table difference between function and stored procedure
| Function | Stored Procedure |
|---|---|
| A function returns a value when it is executed. | A stored procedure does not necessarily return a value. It can execute a set of SQL statements or perform some operations and not return anything. |
| Functions can be used in SELECT, WHERE or HAVING clauses of a SQL query. | Stored procedures cannot be used directly in SELECT, WHERE or HAVING clauses of a SQL query, but they can be called from within a SELECT statement. |
| Functions are deterministic in nature, which means for a given set of inputs, they always produce the same output. | Stored procedures can be deterministic or non-deterministic. |
| Functions can be used in computed columns and constraints. | Stored procedures cannot be used in computed columns and constraints. |
| Functions can be called from within a stored procedure. | Stored procedures can also call other stored procedures, including functions. |