How to loop through several database in SQL server 2005? - sql-server-2005

Question

I have around 50 different databases and inside each of these database there is a table with the same name. Now, I have a written a query which extract selected fields from the table, but I need to manually select the database. How do I write a query so that I can pass database name and pull the data from that table?
Here is my code:
;WITH Review as (
select external_id as sponsorid, name as sponsorname, memberid, startdate, paidamt, code
from test.dev.sraw c left join client.dbo.sponsors s on c.customerid = s.external_id
where year(startdate) >2009 and startdate <> '0001-01-01' and startdate <> '1000-01-01'),
FinalDataCollection as (select sponsorid, sponsorname, count(*) as NbrOfClaims, count(distinct memberid) as NbrOfMembers, month(startdate) as mnth, year(startdate) as yr, sum(cast(paidamt as money)) as dollars, case when code > '0' then 'RX' else 'med' end as category, case when count(distinct memberid)> 0 then sum(cast(paidamt as money))/count(distinct memberid) else 0 end as costpm
from Review
group by sponsorid, sponsorname,year(startdate), month(startdate),case when code > '0' then 'RX' else 'med' end)
select * from FinalDataCollection
UPDATE #1
How do I replace ''SELECT top 5 * FROM '' + #db + ''.dbo.RAW'' of the following query with the above SQL query that start with ;WITH CTE
DECLARE #dbname NVARCHAR(200)
DECLARE #SQLString NVARCHAR (MAX)
SET #SQLString =
'DECLARE #db NVARCHAR(255)
DECLARE DB_CURSOR CURSOR LOCAL FAST_FORWARD FOR
SELECT db.name from sys.databases db WHERE db.name IN
(''A'',''B'',''C'' ) ORDER BY db.name
OPEN DB_CURSOR
FETCH NEXT FROM DB_CURSOR INTO #db
WHILE ##FETCH_STATUS = 0
BEGIN
EXEC(''SELECT top 5 * FROM '' + #db + ''.dbo.RAW'')
FETCH NEXT FROM DB_CURSOR INTO #db
END
CLOSE DB_CURSOR
DEALLOCATE DB_CURSOR'
EXEC sp_executesql #SQLString
Thank you

Answer 1

You could create a stored procedure having one parameter #DbName thus:
CREATE PROCEDURE dbo.GetDataFromMyTable (
#DbName SYSNAME -- or NVARCHAR(128)
)
AS
BEGIN
IF DB_ID(#DbName) IS NOT NULL AND #DbName IN (N'MyDB1', N'MyDB2', N'MyDB3', ...)
BEGIN
DECLARE #SqlStatement NVARCHAR(MAX);
SET #SqlStatement = N'USE ' + QUOTENAME(#DbName) + N'; SELECT t.Col1, t.Col2 FROM dbo.MyTable';
EXEC sp_executesql #SqlStatement;
END
ELSE
RAISERROR('Wrong database.', 16, 1);
END
END;
Notes:
DB_ID(#DbName) IS NOT NULL -- It checks if #DbName exists
#DbName IN (N'MyDB1', N'MyDB2', ..., N'MyDBn') -- It checks if #DbName is on the white list with allowed database (from this point of view, first check is, somehow, redundant).
Why I've used QUOTENAME(#DbName) ? See section Wrapping Parameters with QUOTENAME() and REPLACE(): if the content of #variable is a securable (ex. a database / table) then the recommended wrapper is QUOTENAME(#variable).
You could replace #DbName IN (N'MyDB1', N'MyDB2', ..., N'MyDBn') with exists thus:
EXISTS (
SELECT *
FROM (
SELECT N'MyDB1' UNION ALL
SELECT N'MyDB2' UNION ALL
...
SELECT N'MyDBn'
) dbs(DbName)
WHERE dbs.DbName = #DbName
)
Update #1:
You have to replace
SELECT t.Col1, t.Col2 FROM dbo.MyTable
with
WITH Review as (
select external_id as sponsorid, name as sponsorname, memberid, startdate, paidamt, code
from test.dev.sraw c left join client.dbo.sponsors s on c.customerid = s.external_id
where year(startdate) >2009 and startdate <> ''0001-01-01'' and startdate <> ''1000-01-01''),
FinalDataCollection as (select sponsorid, sponsorname, count(*) as NbrOfClaims, count(distinct memberid) as NbrOfMembers, month(startdate) as mnth, year(startdate) as yr, sum(cast(paidamt as money)) as dollars, case when code > ''0'' then ''RX'' else ''med'' end as category, case when count(distinct memberid)> 0 then sum(cast(paidamt as money))/count(distinct memberid) else 0 end as costpm
from Review
group by sponsorid, sponsorname,year(startdate), month(startdate),case when code > ''0'' then ''RX'' else ''med'' end)
select * from FinalDataCollection