Equipment table Join Sql query

Ignition
1

I have two tables, one is MblEquip and the other is MobileDowntime. The query(below) results only show the Mobile Equipment that had downtime this month it doesn’t show all the equipment. I am wanting to put zero’s for the equipment that doesn’t have any Downtime this month. Any Ideas how to show the other equipment and put zero’s in those rows that are null.

SELECT a.EquipNbr, case when Sum(a.Downtime) is null then 0 else Sum(a.Downtime)end Downtime FROM MobileDowntime (nolock) a
join MblEquip (nolock) b on a.EquipNbr = b.EquipNbr
Where b.DelFlg = 0 and b.EquipNbr != 'Clean Shop' and a.DateTm Between DATEADD(month, DATEDIFF(month, 0, getDate()), 0) and DATEADD(month, DATEDIFF(month, -1, getDate()), -1)
Group By a.EquipNbr Order by a.EquipNbr Asc
2

Use a LEFT join and instead of case use ISNULL(Sum(a.Downtime),0)

3

It gives me the same results as before

4

After digging around on the internet, this is the only way I could find that worked the way I needed it to

Select e.EquipNbr, coalesce(sum(md.Downtime), 0) Downtime
From MblEquip e left join
     MobileDowntime md
     on md.EquipNbr = e.EquipNbr and
        md.DateTm between DATEADD(month, DATEDIFF(month, 0, getDate()), 0) and DATEADD(month, DATEDIFF(month, -1, getDate()), -1)
where e.DelFlg = 0 and e.EquipNbr <> 0000
group by e.EquipNbr 
order by e.EquipNbr Asc;