Stored procedures vs. functions

In many instances you can accomplish the same task using either a stored procedure or a function. Both functions and stored procedures can be custom defined and part of any application. Functions, on the other hand, are designed to send their output to a query or T-SQL statement. For example, User Defined Functions (UDFs) can run an executable file from SQL SELECT or an action query, while Stored Procedures (SPROC) use EXECUTE or EXEC to run. Both are instantiated using CREATE FUNCTION.

To decide between using one of the two, keep in mind the fundamental difference between them: stored procedures are designed to return its output to the application. A UDF returns table variables, while a SPROC can't return a table variable although it can create a table. Another significant difference between them is that UDFs can't change the server environment or your operating system environment, while a SPROC can. Operationally, when T-SQL encounters an error the function stops, while T-SQL will ignore an error in a SPROC and proceed to the next statement in your code (provided you've included

Digg This!     StumbleUpon     Del.icio.us

RELATED CONTENT Database Administration Top load balancing methods for SQL Server Performance implications of transaction log autogrowth in SQL Server The keys to database backup protection for SQL Server Understanding transparent data encryption in SQL Server 2008 Working with sparse columns in SQL Server 2008 Determining the source of full transaction logs in SQL Server Implementing SQL Server 2008 FILESTREAM functionality Improving SQL Server full-text search performance Using the OPENROWSET function in SQL Server New replication features in SQL Server 2008 and what they mean to you SQL Server Stored Procedures Top 10 SQL Server development tips of 2008 SQL Server trigger vs. stored procedure to receive data notification SQL Server errors, failures and other problems fixed from the trenches SQL Server and data manipulation in T-SQL How to use SQL Server 2008 hierarchyid data type SQL Server stored procedures tutorial: Write, tune and get examples Check SQL Server database and log file size with this stored procedure SQL Server source code analysis and management adds database security Configure SQL Server Service Broker for sending stored procedure data Find size of SQL Server tables and other objects with stored procedure

RELATED GLOSSARY TERMS Terms from Whatis.com − the technology online dictionary library  (SearchSQLServer.com) trigger  (SearchSQLServer.com)

RELATED RESOURCES 2020software.com, trial software downloads for accounting software, ERP software, CRM software and business software systems Search Bitpipe.com for the latest white papers and business webcasts Whatis.com, the online computer dictionary

error handling support). You'll also find that although a SPROC can be used in an XML FOR clause, a UDF cannot be.

If you have an operation such as a query with a FROM clause that requires a rowset be drawn from a table or set of tables, then a function will be your appropriate choice. However, when you want to use that same rowset in your application the better choice would be a stored procedure.

There's quite a bit of debate about the performance benefits of UDFs vs. SPROCs. You might be tempted to believe that stored procedures add more overhead to your server than a UDF. Depending upon how your write your code and the type of data you're processing, this might not be the case. It's always a good idea to text your data in important or time-consuming operations by trying both types of methods on them.

Barrie Sosinsky is president of consulting company Sosinsky and Associates (Medfield MA). He has written extensively on a variety of computer topics. His company specializes in custom software (database and Web related), training and technical documentation.