Question

I’m fairly new to SQL server (this is my second post on StackOverflow). I’m currently using SQL Server 2008 R2. I have a few tables that I’ve joined with the following query:

SELECT pt.first_name, pt.last_name, pt.provider_id, 
pt.last_visit_date, pl.last_name
FROM dbo.pm_patient pt
INNER JOIN dbo.ProviderList pl
ON pt.provider_id = pl.provider_id
WHERE pt.last_visit_date >= '02/01/2012' AND pt.last_visit_date <= '02/01/2013'
ORDER BY provider_id

The result of the above query looks something like this:

first_name    last_name    provider_id   last_visit_date   last_name
Smith         John         1             04/25/2012        Johnson
Doe           Jane         1             02/25/2012        Johnson
Davies        Ann          1             03/15/2012        Johnson
Dupree        David        1             11/20/2012        Johnson
Jones         Becky        1             04/21/2012        Smith
Diaz          Mike         1             02/12/2012        Smith
Williams      Allison      1             08/05/2012        Smith
Taylor        Joe          1             10/01/2012        Smith

I would rather simply get the following result:

last_name    NoOfPatients
Johnson      4
Smith        4

Could someone please help me?

Answer 1

Try :

SELECT pl.last_name, count(*) NoOfPatients
FROM dbo.pm_patient pt
INNER JOIN dbo.ProviderList pl
ON pt.provider_id = pl.provider_id
WHERE pt.last_visit_date >= '02/01/2012' AND pt.last_visit_date <= '02/01/2013'
GROUP BY pl.last_name