MS Access - SQL LEFT JOIN multiple conditions

Question

I have this code which is working fine except that I need to add one more condition:

SELECT     record1.*, 
           tbl_mpsregion.maintenanceteam, 
           tbl_mpsregion.regionmps 
INTO       tbl_sapforecast 
FROM       tbl_mpsregion 
RIGHT JOIN 
           ( 
                     SELECT    sap_ip19.*, 
                               dateserial(RIGHT(trim([SAP_IP19].[PlanDate]),4),mid(trim([SAP_IP19].[PlanDate]),4,2),LEFT(trim([SAP_IP19].[PlanDate]),2)) AS [DATE/FORECAST], 
                               tbl_labourstandard.re, 
                               tbl_labourstandard.manning, 
                               tbl_labourstandard.skillset AS skillset, 
                               tbl_regionmapping.maintenanceplant, 
                               tbl_regionmapping.area, 
                               tbl_regionmapping.region AS region, 
                               tbl_regionmapping.onresponse, 
                               [RE]*[Manning]/60 AS hours 
                     FROM      (sap_ip19 
                     LEFT JOIN tbl_labourstandard 
                     ON        ( 
                                         LEFT(sap_ip19.[Task list description],3) = tbl_labourstandard.jemenawc) 
                     AND       ( 
                                         sap_ip19.[MntPlan] = cdbl(tbl_labourstandard.supplypoint ))) 
                     LEFT JOIN tbl_regionmapping 
                     ON        sap_ip19.location = cdbl([Tbl_RegionMapping].[FittersDistricts])) AS record1 
ON         ( 
                      record1.region = [Tbl_MPSRegion].[Region]) 
AND        ( 
                      record1.skillset = [Tbl_MPSRegion].[Skillset]) ;

Criteria to add is: If SAP_IP19.MntPlan does not match Tbl_LabourStandard.SupplyPoint then use 0 for Tbl_LabourStandard.SupplyPoint. I am not using Server 2000 so using CASE is not a solution. Have tried IIF and SWITCH but they are not taking query to sleep mode (not evaluating). I read that JOINS with IIF or SWITCH cannot be used. Please help!

Answer 1

You should be able to add if's or switches but you could always handle this with an OR - it's not the most performance friendly but it should get the job done, example below:

LEFT JOIN tbl_labourstandard
ON 
(LEFT(sap_ip19.[Task list description],3) = tbl_labourstandard.jemenawc) 
AND 
((Tbl_LabourStandard.SupplyPoint = SAP_IP19.MntPlan AND
sap_ip19.[MntPlan] = cdbl(tbl_labourstandard.supplypoint)) 
OR (sap_ip19.[MntPlan] = 0))