Difference between Stored procedures and User Defined functions[UDF]

shabbir's Avatar author of Difference between Stored procedures and User Defined functions[UDF]
This is an article on Difference between Stored procedures and User Defined functions[UDF] in Database.
The definition of stored procedure as from WIKIPEDIA

Stored procedure
A stored procedure is a program (or procedure) which is physically stored within a database. They are usually written in a proprietary database language like PL/SQL for Oracle database or PL/PgSQL for PostgreSQL. The advantage of a stored procedure is that when it is run, in response to a user request, it is run directly by the database engine, which usually runs on a separate database server. As such, it has direct access to the data it needs to manipulate and only needs to send its results back to the user, doing away with the overhead of communicating large amounts of data back and forth.

User-defined function
A user-defined function is a routine that encapsulates useful logic for use in other queries. While views are limited to a single SELECT statement, user-defined functions can have multiple SELECT statements and provide more powerful logic than is possible with views.

In SQL Server 2000
User defined functions have 3 main categories
  1. Scalar-valued function - returns a scalar value such as an integer or a timestamp. Can be used as column name in queries
  2. Inline function - can contain a single SELECT statement.
  3. Table-valued function - can contain any number of statements that populate the table variable to be returned. They become handy when you need to return a set of rows, but you can't enclose the logic for getting this rowset in a single SELECT statement.
Differences between Stored procedure and User defined functions
  1. UDF can be used in the SQL statements anywhere in the WHERE/HAVING/SELECT section where as Stored procedures cannot be.
  2. UDFs that return tables can be treated as another rowset. This can be used in JOINs with other tables.
  3. Inline UDF's can be though of as views that take parameters and can be used in JOINs and other Rowset operations.
  4. Of course there will be Syntax differences and here is a sample of that
Stored procedure
Code: SQL
CREATE PROCEDURE dbo.StoredProcedure1
  /*
     (
      @parameter1 datatype = default value,
      @parameter2 datatype OUTPUT
     )
  */

  AS
     /* SET NOCOUNT ON */
     RETURN
User defined functions
Code: SQL
CREATE FUNCTION dbo.Function1
     (
     /*
     @parameter1 datatype = default value,
     @parameter2 datatype
     */

     )
  RETURNS /* datatype */
  AS
     BEGIN
      /* sql statement ... */
     RETURN /* value */
     END
0
sunflowerhot's Avatar, Join Date: Jun 2007
Newbie Member
super
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Linda_rose's Avatar, Join Date: Jun 2007
Newbie Member
Where can i find detail information on this topic ?????

Linda
<<Link Removed>>

Last edited by shabbir; 23Jun2007 at 19:00.. Reason: Confine links to signature only
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shabbir's Avatar, Join Date: Jul 2004
Go4Expert Founder
Linda, Please confine your links to signatures only.
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krishnakishu's Avatar, Join Date: Jul 2007
Newbie Member
Can i get a link where i can clearly identify the difference between a stored procedure and a function?
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shabbir's Avatar, Join Date: Jul 2004
Go4Expert Founder
Quote:
Originally Posted by krishnakishu
Can i get a link where i can clearly identify the difference between a stored procedure and a function?
Your web browser shows the link.
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ERUM's Avatar, Join Date: Sep 2007
Go4Expert Member
I did not get the following statment ....


UDF can be used in the SQL statements anywhere in the WHERE/HAVING/SELECT section where as Stored procedures cannot be.

Could any one please more focus on it
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shabbir's Avatar, Join Date: Jul 2004
Go4Expert Founder
You can have UDF in the condition of where clause.
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ERUM's Avatar, Join Date: Sep 2007
Go4Expert Member
i have read some where that significant difference between them is that UDFs can't change the server environment or your operating system environment, while a SPROC can

so my question is that how sp can change server environment or your operating system environment .

I would be grateful to any one if descibe by any example hwo this happens
0
vikas1234's Avatar, Join Date: Aug 2008
Go4Expert Member
There is nothing like operating system environment correct me if I am wrong it is just the context environment in which program is executing