subquerying in WHERE/Joining 3 tables, 2 for records and one for number, returns no result/fails - MSAccess - sql

Question

My query does return any records. Depending on how I write it, it returns no records or all records, although I don't have the code that just returned everything.
I need to pull data from two sources with actual records, and a third table which has project-wide information not specific to any records. I need to filter out records which are greater than the Miles_Budgeted variable.
This returns no records, although if I replaces param.Miles_Budgeted with a numeric value e.g. 1000, it filters to the desired records.
SELECT
a.sort_id,
a.l1l2,
a.rtot_pct_oftot_miles,
b.sumofeq,
b.c_per_mile,
b.sumofo_total,
a.cpminrmd,
a.RunTotMiles,
param.Miles_Budgeted
FROM
(SELECT (p.Budget_Cost_Targ / p.Project_Cost_Per_Mi) AS Miles_Budgeted FROM Tbl_Project_Parameters as p) AS param,
qry_par_l2_by_cpermi AS a
INNER JOIN
qry_l2 AS b
ON a.l1l2 = b.l1l2
WHERE
((a.RunTotMiles) <=
(Param.Miles_Budgeted
)
)
ORDER BY
a.sort_id;
This variant of the query does not run (Syntax Error in FROM Clause)
SELECT
a.sort_id,
a.l1l2,
a.rtot_pct_oftot_miles,
b.sumofeq,
b.c_per_mile,
b.sumofo_total,
a.cpminrmd,
a.runtotmiles,
param.miles_budgeted
FROM (
(
SELECT (p.budget_cost_targ / p.project_cost_per_mi) AS miles_budgeted
FROM tbl_project_parameters AS p ) AS param
INNER JOIN qry_par_l2_by_cpermi AS a )
INNER JOIN qry_l2 AS b
ON a.l1l2 = b.l1l2
AND (
a.runtotmiles) <= ( param.miles_budgeted )
ORDER BY a.sort_id;
This also returns no records:
SELECT
a.sort_id,
a.l1l2,
a.rtot_pct_oftot_miles,
b.sumofeq,
b.c_per_mile,
b.sumofo_total,
a.RunTotMiles,
a.cpminrmd
FROM
qry_par_l2_by_cmipermi AS a
INNER JOIN
qry_l2 AS b
ON a.l1l2 = b.l1l2
WHERE
(
((a.RunTotMiles) <=
(
SELECT
(p.Budget_Cost_Targ / p.Project_Cost_Per_Mi) AS Budgeted_Miles
FROM
Tbl_Project_Parameters AS p
)
)
)
ORDER BY
a.sort_id;
Again, if
SELECT
(p.Budget_Cost_Targ / p.Project_Cost_Per_Mi) AS Budgeted_Miles
FROM
Tbl_Project_Parameters AS p
is replaces with a numeric value, the query returns the correct records. I have tried surrounding the subq or field with val() or Format(,"Standard") but this does not see to fix the issue; a separate query with just the relevant code returns the correct Budgeted_Miles as 1000 as it should.
Any thoughts appreciated.

Answer 1

Have you tried limiting that subquery to return only one record? I know some versions of SQL don't like when you try comparing the results of a SELECT to a single value.
I believe the syntax for MS Access would use "TOP":
SELECT TOP 1
(p.Budget_Cost_Targ / p.Project_Cost_Per_Mi) AS Budgeted_Miles
FROM
Tbl_Project_Parameters AS p