Distinct Count?

Question

I'm using SQL Server Express 2014 and I need to test some queries prior to using them in a full version (I've not decided which to move over to yet). I have a table with an inventory of virtual machines and I need to list the count of them per cluster. Each
listed virtual machine has more than one entry though as it lists a record for each disk so I need to SELECT DISTINCT on the virtual machine name to eliminate duplicate entries and list the count next the clustername.
Here's the schema:
CREATE TABLE [VMs](
[VMID] [int] IDENTITY(1,1) NOT NULL,
[VMName] [varchar](100) NULL,
[Template] [varchar](100) NULL,
[PowerState] [varchar](100) NULL,
[ClusterName] [varchar](100) NULL,
[Disk] [int] NULL,
[DiskPartition] [varchar](70) NULL,
[DiskSizeGB] [decimal](10, 3) NULL,
CONSTRAINT [PK_VMs] PRIMARY KEY CLUSTERED
[VMID] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
Desired output would be something like:
ClusterName VMName
Cluster01 15
Cluster02 18
Cluster03 20
I tried the below code but it resulted in duplicates for ClusterName
SELECT DISTINCT ClusterName,COUNT(VMName)
FROM VMs
GROUP BY VMName,ClusterName
I hope this is enough information
Thanks in advance
Adam

Answer 1

You can do:
SELECT ClusterName, COUNT(*)
FROM VMs
GROUP BY ClusterName
SELECT ClusterName, COUNT(DISTINCT VMNname)
FROM VMs
GROUP BY ClusterName
Example:
SELECT ProductSubcategoryID, TotCount = COUNT(*),
ColorCount = COUNT(DISTINCT Color)
FROM Production.Product
WHERE ProductSubcategoryID IS NOT NULL
GROUP BY ProductSubcategoryID
ORDER BY ProductSubcategoryID;
ProductSubcategoryID TotCount ColorCount
1 32 2
2 43 3
3 22 2
4 8 0
5 3 0
Kalman Toth Database & OLAP Architect
SQL Server 2014 Database Design
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