Parameters in Microsoft Access - sql

Question

I'm really confused with how parameters work in Microsoft Access. I know that parameters are supposed to be used to allow a user to type in values when the query is run - instead of having to modify the query for each instance.
So, let's use the following example.
SELECT countyTable.countyName, Sqr((69.1*(46.47-avgLatitude))^2+(69.1*(-90.17-avgLongitude)*Cos(avgLatitude/57.3))^2) as Distance
FROM countyTable
WHERE ((([avgLatitude]-5)<46.47) AND (([avgLatitude]+5)>46.47) AND (([avgLongitude]-5)<-90.17) AND (([avgLongitude]+5)>-90.17))
ORDER BY Sqr((69.1*(46.47-avgLatitude))^2+(69.1*(-90.17-avgLongitude)*Cos(avgLatitude/57.3))^2), countyTable.countyName
1) I am SELECTing a column that contains the SQR function. I also have that column named as 'Distance'. However, when I try to ORDER BY on said column - and refer to it as 'Distance' - it asks for a value instead of sorting on that column. The only way I can get the query to ORDER BY is to duplicate the expression from the SELECT line. This seems unnecessary.
2) Right now, I have some values hard-coded in. I could care less about the values '57.3' and '69.1' However, for '46.47' I would like to replace with 'x2' and -90.17 with 'y2'. How I've been trying to write this with parameters, Access asks for values for each instance of 'x2' and 'y2'. This doesn't help me at all, so I have them hardcoded in.
Any help at all? Thanks!

Answer 1

1) I am SELECTing a column that contains the SQR function. I also have that column named as 'Distance'. However, when I try to ORDER BY on said column - and refer to it as 'Distance' - it asks for a value instead of sorting on that column. The only way I can get the query to ORDER BY is to duplicate the expression from the SELECT line. This seems unnecessary.
Yes Access does a poor job. Every real DBMS now supports ordering by the column alias created in the SELECT clause. To do this in Access, you can either do what you are doing (repeat the expression) or subquery it, e.g.
select a,b,c
from (
select a, b, a+b as C
from sometable
) AS SUBQUERIED
order by c
2) How I've been trying to write this with parameters, Access asks for values for each instance of 'x2' and 'y2'.
You're doing it wrong. Access should prompt only once. If you have a query like this
select a, b, a+b as C
from sometable
where a > [x] and y > [x]
It will see both [x]'s as being the same - and only one prompt for both. Just make sure they are spelt exactly the same.

Answer 2

If you wanted something like this simplified example:
SELECT
countyTable.countyName,
Sqr((69.1*(46.47-avgLatitude))^2+(69.1*(-90.17-avgLongitude)*Cos(avgLatitude/57.3))^2) as Distance
FROM countyTable
ORDER BY Distance;
For the ORDER BY you can reference that complex Distance expression by its ordinal position in the field list.
SELECT
countyTable.countyName,
Sqr((69.1*(46.47-avgLatitude))^2+(69.1*(-90.17-avgLongitude)*Cos(avgLatitude/57.3))^2) as Distance
FROM countyTable
ORDER BY 2;
That method is supported at least since Jet 4 (Access 2000), and also by the newer ACE database engine.