Rewriting Stored Procedures as Functions

expersts,  am reading about function. I don understand this
     Its primary purpose is to build intermediate results
plase, can you give me transact sql
enrique_aeoAsked:
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TimBusiness Systems AnalystCommented:
A function will accept only an input parameter and has only one return value.

A stored procedure will accept input and output parameters and can have multiple output values.


The code below is from MSDN http://msdn.microsoft.com/en-us/library/ms187926.aspx

CREATE { PROC | PROCEDURE } [schema_name.] procedure_name [ ;number ] 
    [ { @parameter [ type_schema_name. ] data_type } 
        [ VARYING ] [ = default ] [ OUT | OUTPUT ] [READONLY]
    ] [ ,...n ] 
[ WITH <procedure_option> [ ,...n ] ]
[ FOR REPLICATION ] 
AS { [ BEGIN ] sql_statement [;] [ ...n ] [ END ] }
[;]

<procedure_option> ::= 
    [ ENCRYPTION ]
    [ RECOMPILE ]
    [ EXECUTE AS Clause ]

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dqmqCommented:
>It's primary function is to build intermediate results

No, I don't think so...
A function is just some stored SQL that returns a single value.  For example, GETDATE() returns the current date and SYSTEM_USER() return the current login. Many functions accept arguments, for example UPPER(string) accepts a string argument and returns the same string converted to upper case.  

SQL server comes with many built-in functions, but also supports user defined functions (UDF's), so you can write your own.  You write those using TSQL  (or any CLR language).  For example, here's a simple function that uses the CAST AND DATEADD builtin functions to return tomorrows date.

Create Function dbo.GetTomorrow ()
Returns date
as
begin
return (dateadd(d,1,cast(cast(getdate() as int) as datetime)))
end
go

select getdate() as today, dbo.getTomorrow() as tomorrow

Generally speaking, stored procedures cannot be converted to functions because functions have many limitations and they return results a different way.  












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Microsoft SQL Server 2008

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