从子查询SQL Server 2008更新

Question

I have tblPatient with the county name and state name in the table. I have a look up table for both county name and state name and I'm trying to normalize my tblPatient, its structure is

As you can imagine, different states sometimes share county names. To deal with this I'm using the query

select patientid, admissionDate, dischargeDate, patientState, patientCounty
from tblPatient
where patientState='AL'

I'd like to update tblPatient.patientCounty to equal tblStateCounties.countyCode where patientCounty and countyName are the same.

I haven't had a dummy's version of how to use rollback yet, but this looks correct to me, yet I don't want to be committed to a possibly silly error.

update tblPatient
set tblPatient.patientCounty=tblStateCountes.countyCode
from 
(
select patientID, admissionDate, dischargeDate, patientState, patientCounty from tblPatient
where patientState='AL'
) as t
inner join on tblStateCounties.countyName=tblPatient.countyName

Answer 1

The query you wrote won't parse (you can check that easily enough) because you're missing the FROM clause in your sub query.You'd also need to JOIN on t.tblPatient and also you'd need tblPatient in your main FROM clause.

You can use the query below to update your table.

UPDATE tblPatient 
SET    tblPatient.patientCounty = tblStateCounties.countyCode 
FROM   tblPatient 
       INNER JOIN tblStateCounties 
               ON tblStateCounties.countyName = tblPatient.patientCounty 
WHERE  patientState = 'AL' 
       AND tblStateCounties.stateCode = '01'; 

You'll notice I removed the subquery and used a simple where clause. Since you noted that counties can share names so you will need to filter for the tblStateCounties.stateCode as well

Also consider making a table mapping of StateNames to StateCode (if you don't have that already)

DEMO