Left Join not working - sql

Question

I am a SQL Server beginner and so I have been using MS Access to create queries and then have been amending them for SQL Server.
I have created a query which includes a left join, which works perfectly in Access but when I copy the SQL code across to SQL Server it does not show the null values and I cannot work out why.
I want to show all of the attribute values whether they include a value or not. Can anyone help? The code is as follows:
SELECT DISTINCT
tbLease.LeaseTitle
, tbAttributeValue.AttributeTemplateDefinitionLinkID
, tbAttributeValue.Value
FROM
((((tbBusinessUnit
LEFT JOIN
tbAttributeValue ON tbBusinessUnit.BusinessUnitID = tbAttributeValue.ParentID)
INNER JOIN
tbBuildingLinkBusinessUnit ON tbBusinessUnit.BusinessUnitID = tbBuildingLinkBusinessUnit.BusinessUnitID)
INNER JOIN
tbBuilding ON tbBuildingLinkBusinessUnit.BuildingID = tbBuilding.BuildingID)
INNER JOIN
(tbUnitLocation
INNER JOIN
tbUnit ON tbUnitLocation.UnitID = tbUnit.UnitID)
ON tbBuilding.BuildingID = tbUnitLocation.LocationID)
INNER JOIN
tbLease ON tbUnit.UnitID = tbLease.UnitID
WHERE
(((tbAttributeValue.AttributeTemplateDefinitionLinkID) = 30
Or (tbAttributeValue.AttributeTemplateDefinitionLinkID) = 31
Or (tbAttributeValue.AttributeTemplateDefinitionLinkID) = 32));

Answer 1

Hard to say what you want without some examples but you might want this:
WHERE coalesce(tbAttributeValue.AttributeTemplateDefinitionLinkID,30) in (30,31,32);
This will give you items where AttributeTemplateDefinitionLinkID is null
(that is it did not join on the left join) OR is one of those 3 values.
Right now if you don't join with the left join it will not display that row because of the where condition, so your left join is the same as an inner join.

Answer 2

The NULL values you would normally see with a left join are getting filtered out by your WHERE clause.
Any time you add filters to a WHERE clause that apply to an outer joined table, it will effectively make it the same as an inner join unless you include NULL values as an option in your where clause as well.
SELECT DISTINCT
tbLease.LeaseTitle,
tbAttributeValue.AttributeTemplateDefinitionLinkID,
tbAttributeValue.Value
FROM
tbBusinessUnit
LEFT JOIN tbAttributeValue ON tbBusinessUnit.BusinessUnitID = tbAttributeValue.ParentID
INNER JOIN tbBuildingLinkBusinessUnit ON tbBusinessUnit.BusinessUnitID = tbBuildingLinkBusinessUnit.BusinessUnitID
INNER JOIN tbBuilding ON tbBuildingLinkBusinessUnit.BuildingID = tbBuilding.BuildingID
INNER JOIN tbUnitLocation ON tbBuilding.BuildingID = tbUnitLocation.LocationID
INNER JOIN tbUnit ON tbUnitLocation.UnitID = tbUnit.UnitID
INNER JOIN tbLease ON tbUnit.UnitID = tbLease.UnitID
WHERE
tbAttributeValue.AttributeTemplateDefinitionLinkID in (30, 31, 32)
or tbAttributeValue.AttributeTemplateDefinitionLinkID is null

Answer 3

Move the right table filters from where clause to ON condition when you are using Left Outer Join else Left join will be implicitly converted to INNER JOIN. Try this
SELECT DISTINCT tblease.leasetitle,
tbattributevalue.attributetemplatedefinitionlinkid,
tbattributevalue.value
FROM tbbusinessunit
LEFT JOIN tbattributevalue
ON tbbusinessunit.businessunitid = tbattributevalue.parentid
AND ( tbattributevalue.attributetemplatedefinitionlinkid IN
( 30, 31, 32 )
OR tbattributevalue.attributetemplatedefinitionlinkid IS
NULL )
INNER JOIN tbbuildinglinkbusinessunit
ON tbbusinessunit.businessunitid =
tbbuildinglinkbusinessunit.businessunitid
INNER JOIN tbbuilding
ON tbbuildinglinkbusinessunit.buildingid = tbbuilding.buildingid
INNER JOIN tbunitlocation
ON tbbuilding.buildingid = tbunitlocation.locationid
INNER JOIN tbunit
ON tbunitlocation.unitid = tbunit.unitid
INNER JOIN tblease
ON tbunit.unitid = tblease.unitid