Call User-defined Function on Linked Server :SQL Server

If you try to invoke a user-defined function (UDF) through a linked server in SQL Server by using a "four-part naming" convention (server.database.dbo.Function), you may receive error message. 

The reason is User-defined function calls inside a four-part linked server query are not supported in SQL Server. Thats why error message indicates that the syntax of a Transact-SQL statement is incorrect. 

To work around this problem, use the Openquery function instead of the four-part naming convention. For example, instead of the following query

Select * from Linked_Server.database.dbo.Function(10)

run a query with the Openquery function:

Select * from Openquery(Linked_Server,'select database.dbo.Function(10)')

If the user-defined function takes variable or scalar parameters, you can use the sp_executesql stored procedure to avoid this behavior. 

For example:

exec Linked_Server.database.dbo.sp_executesql N'SELECT 
database.dbo.Function(@input)',N'@input int',@input=10

but if you want to use it in a select statement (within some Stored Procedure), then this EXEC command will create some problems for you :)

However this could be resolve easily by creating a user-defined function in your database (not the linked server one)

CREATE FUNCTION [dbo].Function_Name(@Parameter INT) 

RETURNS VARCHAR(8000)

AS

BEGIN

DECLARE @word sysname

EXEC LinkedServer.DatabaseName.dbo.sp_executesql

N'SELECT DatabaseName.dbo.Function_Name(@Parameter)' --dynamic sql query to execute

,N'@Parameter int' --parameter definitions

,@Parameter=@word OUTPUT --assigning the caller procs local variable to the dynamic parameter

RETURN @word

END

In order to run the above function, you have set RPC Out value of that particular linked server to be True.