How to return varchar value from a function

Question

I written the following function.

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
Create FUNCTION NameFunction
(
    @eid int
)
RETURNS varchar
AS
BEGIN
            


        

Answer 1

Change your RETURN type to include a length, at this point it is just returning 1 character:

RETURNS varchar(100)

Full code:

SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
Create FUNCTION NameFunction
(
    @eid int
)
RETURNS varchar(100) -- or whatever length you need
AS
BEGIN
    Declare @logid varchar(50);
    SELECT @logid = E.LoginId from HumanResources.Employee As E
    where E.BusinessEntityID = @eid

    RETURN  @logid

END
GO

Answer 2

RETURNS varchar should be RETURNS varchar(50).

varchar without a length specified is interpreted as varchar(1) in this context (and as varchar(30) in the context of a CAST).

BTW: Scalar UDFs that do data access can be performance killers. You might want to consider at least rewriting this as an inline TVF so that the optimiser has more options.