SQL Select DISTINCT GROUP BY Weekday in Access - sql

Question

I am trying to Count the distinct Number of UserID's in a table for each Weekday (e.g. 545 UserID's on Weekday 1 = Monday, 120 UserID's on Weekday 2 = Tuesday etc.). I am doing this in Access Visual Basic, but the syntax should be universal to SQL. Here is my VB Code:
sSQL = " SELECT Weekday(" & tablename & ".[DATE]) AS WEEKDAY, Count(DISTINCT " & tablename & ".[UserID]) AS User_COUNT"
sSQL = sSQL & " FROM " & tablename
sSQL = sSQL & " GROUP BY Weekday(" & tablename & ".[DATE])"
qdf.SQL = sSQL
The plain SQL Syntax should look like this (edited based on comments & test):
SELECT Weekday(tbl.[Date]) AS WEEKDAY, Count(DISTINCT tbl.[UserID]) AS User_COUNT
FROM tbl
GROUP BY Weekday(tbl.[Date])
..whereas [Date] is a field in tbl formatted as Datetime and [UserID] is a field formatted as Long (with duplicates).
When I try to run the command it tells me "Missing Operator in Query-Syntax.."
Is this a problem of my VB Code or is the SQL Syntax wrong?

Answer 1

MS Access database engine does not support COUNT(DISTINCT ...).
To workaroud it, please see this thread: SQL : how can i count distinct record in MS ACCESS where author suggests to solve issue by using subquery:
SELECT
user_id
, COUNT(*) AS count_distinct_clients
FROM
( SELECT DISTINCT
user_id,
client_id
FROM tbl_sActivity
) AS tmp
GROUP BY
user_id ;
Change the query code to your needs.
[EDIT]
SELECT
wday, COUNT(UserId) AS count_distinct_users
FROM
( SELECT DISTINCT WEEKDAY([Date]) AS wday, UserId
FROM tblName
) AS tmp
GROUP BY
wday;