MS Access - Query Refactoring Assistance - sql

Question

I have a page in one of my client's websites that generates an extensive report pulling data from numerous tables throughout the website's MS Access database. One of the unfortunate architectural issues of the website is the existence of two nearly identical tables that represent the same "type" of data, but one is an "old" version and the other is a "new" version. When the report is generated I need to perform some aggregate operations on the two similar tables. The initial query joined these tables into the rest of the data and called the appropriate aggregate functions on the joined tables. Soon I realized that a join would not work because the two tables do not necessarily have the same row count, thus causing the aggregate function to improperly group the rows from both tables...
Were this MSSQL or MySQL I would probably create a VIEW containing the composite data from both tables, but unfortunately I'm stuck in MS Access where such "novel" concepts do not exist... The solution I was able to come up with works, but has got to be some of the ugliest SQL I have ever seen. Basically, I create a SQL query including all of the appropriate columns from multiple joined tables and one of the two similar tables. Then I create a second SQL query containing all of the same fields and join the other similar table. Finally, I UNION the two queries and wrap them into a subquery within the FROM clause of an outer query.
The end result is a massive query with a ton of duplicate selects that I included only because of the need to aggregate data from the two similar tables. I really would like to refactor the query into something less awful, but I'm not sure where to start... Any advice?
SELECT contractid,
pholderid,
policyholdername,
policyholdercity,
policyholderstate,
vehicleyear,
vehiclemake,
vehiclemodel,
Iif(claimmileage > vehiclemileage, claimmileage, vehiclemileage) AS mileage,
clientname,
contracttype,
contractmonths,
wholesaleprice,
begindate,
cancelleddate,
cancelledalphatotal,
paiddate,
voided,
Sum(claimscost) AS totalclaimscost,
Sum(claimscount) AS totalclaimscount,
DateAdd('m', contractmonths, begindate) AS expirationdate,
Iif(paiddate IS NOT NULL AND contractmonths > 0,
Iif(voided = true,
Iif(cancelleddate IS NOT NULL,
Iif(((cancelleddate - begindate) / (364.25 / 12)) >= contractmonths,
1,
((cancelleddate - begindate) / (364.25 / 12)) / contractmonths),
Iif(((Date() - begindate) / (364.25 / 12)) >= (contractmonths),
1,
((Date() - begindate) / (364.25 / 12)) / contractmonths)),
((Date() - begindate) / (364.25 / 12)) / contractmonths),
0) AS earnedfactor,
(earnedfactor * wholesaleprice) AS earnedpremium,
Iif(voided = true, 0, (wholesaleprice - earnedpremium)) AS unearnedpremium,
Iif(voided = true AND cancelledalphatotal IS NOT NULL, cancelledalphatotal, 0) AS refund,
Iif(earnedpremium > 0,totalclaimscost / earnedpremium, 0) AS lossratio
FROM (SELECT contracts.id AS contractid,
policyholders.id AS pholderid,
policyholders.firstname
+ ' '
+ policyholders.lastname AS policyholdername,
policyholders.city AS policyholdercity,
policyholders.state AS policyholderstate,
vehicles.yr AS vehicleyear,
vehicles.make AS vehiclemake,
vehicles.model AS vehiclemodel,
vehicles.mileage AS vehiclemileage,
clients.coname AS clientname,
contracttypes.name AS contracttype,
coverageavailable.contractmonths AS contractmonths,
contracts.contractwholesalecost AS wholesaleprice,
contracts.begindate AS begindate,
contracts.cancelledon AS cancelleddate,
contracts.cancelledalphatotal AS cancelledalphatotal,
contracts.paidon AS paiddate,
contracts.voided AS voided,
Sum(Iif(claims.totalrepaircost IS NULL,0,claims.totalrepaircost)) AS claimscost,
Count(claims.id) AS claimscount,
Max(Iif(claims.currentmileage IS NULL,0,claims.currentmileage)) AS claimmileage
FROM claims
RIGHT JOIN (coverageavailable
INNER JOIN ((((policyholders
INNER JOIN clients
ON policyholders.clientid = clients.id)
INNER JOIN contracts
ON policyholders.id = contracts.policyholderid)
INNER JOIN vehicles
ON contracts.vehicleid = vehicles.id)
INNER JOIN contracttypes
ON contracts.contracttypeid = contracttypes.id)
ON coverageavailable.id = contracts.termid)
ON claims.policyholderid = policyholders.id
WHERE contractmonths > 0
AND contracts.begindate IS NOT NULL
AND contracttypes.id <> 3
GROUP BY contracts.id,
policyholders.id,
policyholders.firstname,
policyholders.lastname,
policyholders.city,
policyholders.state,
vehicles.yr,
vehicles.make,
vehicles.model,
vehicles.mileage,
clients.coname,
contracttypes.name,
coverageavailable.contractmonths,
contracts.contractwholesalecost,
contracts.begindate,
contracts.cancelledon,
contracts.paidon,
contracts.voided,
contracts.cancelledalphatotal
UNION
SELECT contracts.id AS contractid,
policyholders.id AS pholderid,
policyholders.firstname
+ ' '
+ policyholders.lastname AS policyholdername,
policyholders.city AS policyholdercity,
policyholders.state AS policyholderstate,
vehicles.yr AS vehicleyear,
vehicles.make AS vehiclemake,
vehicles.model AS vehiclemodel,
vehicles.mileage AS vehiclemileage,
clients.coname AS clientname,
contracttypes.name AS contracttype,
coverageavailable.contractmonths AS contractmonths,
contracts.contractwholesalecost AS wholesaleprice,
contracts.begindate AS begindate,
contracts.cancelledon AS cancelleddate,
contracts.cancelledalphatotal AS cancelledalphatotal,
contracts.paidon AS paiddate,
contracts.voided AS voided,
Sum(Iif(claim.inspector1paidout IS NULL,0,claim.inspector1paidout))
+ Sum(Iif(claim.inspector2paidout IS NULL,0,claim.inspector2paidout))
+ Sum(Iif(claim.mechanicpaidout IS NULL,0,claim.mechanicpaidout))
+ Sum(Iif(claim.partdealerpaidout IS NULL,0,claim.partdealerpaidout)) AS claimscost,
Count(claim.id) AS claimscount,
Max(Iif(claim.mileage IS NULL,0,claim.mileage)) AS claimmileage
FROM claim
RIGHT JOIN (coverageavailable
INNER JOIN ((((policyholders
INNER JOIN clients
ON policyholders.clientid = clients.id)
INNER JOIN contracts
ON policyholders.id = contracts.policyholderid)
INNER JOIN vehicles
ON contracts.vehicleid = vehicles.id)
INNER JOIN contracttypes
ON contracts.contracttypeid = contracttypes.id)
ON coverageavailable.id = contracts.termid)
ON claim.contractid = contracts.id
WHERE contractmonths > 0
AND contracts.begindate IS NOT NULL
AND contracttypes.id <> 3
GROUP BY contracts.id,
policyholders.id,
policyholders.firstname,
policyholders.lastname,
policyholders.city,
policyholders.state,
vehicles.yr,
vehicles.make,
vehicles.model,
vehicles.mileage,
clients.coname,
contracttypes.name,
coverageavailable.contractmonths,
contracts.contractwholesalecost,
contracts.begindate,
contracts.cancelledon,
contracts.paidon,
contracts.voided,
contracts.cancelledalphatotal)
GROUP BY contractid,
pholderid,
policyholdername,
policyholdercity,
policyholderstate,
vehicleyear,
vehiclemake,
vehiclemodel,
vehiclemileage,
clientname,
contracttype,
contractmonths,
wholesaleprice,
begindate,
cancelleddate,
cancelledalphatotal,
paiddate,
voided,
Iif(claimmileage > vehiclemileage, claimmileage, vehiclemileage)
ORDER BY clientname,
begindate DESC
Hopefully all that makes at least some sense...

Answer 1

QueryDef in Access, is similar to a VIEW in other RDBMS.
Based on the first glance, it is better to get the UNION part of the query in a querydef.