UDF in MS SQL Server returning a query starting with “with” cause

Question

This is a perfectly valid SQL Query and works nicely (for e.g.) in Microsoft SQL Server 2014:

with t as (select 'a' as attr) select * from t

it returns a, surely one can simplify it and drop the with part, but that's not the point, the point is to find out a smallest example that illustrates the need/problem. I can pack part of it as a UDF:

CREATE PROCEDURE x(@__employee_id uniqueidentifier)
AS
RETURN (select 'a' as attr);

How can I pack a query that has with block? My aim is to achieve something like:

CREATE PROCEDURE x (@__employee_id uniqueidentifier)
AS
RETURN (
    with t as (select 'a' as attr) select * from t
);

however sql server does not like it, firing an error:

Msg 156, Level 15, State 1, Procedure x, Line 4 [Batch Start Line 0]
Incorrect syntax near the keyword 'with'.

Answer 1

1. you are mixing procedure and function

2. for UDF, your syntax should be

   CREATE or alter function x (@__employee_id uniqueidentifier) returns table AS RETURN ( with t as (select 'a' as attr) select * from t );

Answer 2

Drop the return keyword as suggested in how to return a table from a stored procedure:

CREATE PROCEDURE xx (@__employee_id uniqueidentifier)
AS
    with t as (select 'a' as attr) select * from t