My guess is stored procedures

Greetings All!
I just started playing with MS SQL and was wondering how i could
possibly do the following for example.
I do a 'SELECT source FROM history' and that gives me a list of
sources. Now i want to run a SELECT for each source i received from
the previous SELECT.

For further clarity, in programming terms, it would be just like
looping through an array.

Thanks Guys,
PatricePlease define what you mean by "run a SELECT for each source". It might help
to post the DDL (CREATE TABLE statements) and some sample data (INSERT
statements) for your table(s). Also, show the end-result you would want to
get from that sample data.

In general in SQL you should try to minimise procedural code such as loops.
SQLServer is optimised for set-based queries. If you want to SELECT a set of
rows for each "source" then you can probably write that query as a JOIN to
one or more tables.

For example (from the Pubs database). To retrieve all the Titles for each
Author:

SELECT A.au_fname+' '+A.au_lname AS author, T.title
FROM Authors AS A
JOIN TitleAuthor AS B
ON A.au_id = B.au_id
JOIN Titles AS T
ON B.title_id = T.title_id
ORDER BY A.au_lname, A.au_fname

--
David Portas
SQL Server MVP
--|||Hi David,
Sorry for the lack of clarity.

My plan is to detect if any users login from more than 3 sources.

I have a history table
CREATE TABLE history(client_id int, when datetime, source varchar(20))

After some inserts a SELECT * FROM history looks like

-------------
|client_id | when | source |
-------------
|1010 | <date> | 202.22.21.33 |
-------------
|1818 | <date> | 192.10.22.31 |
-------------
|1542 | <date> | 222.452.1.36 |
-------------
|1010 | <date> | 192.22.21.33 |
-------------
|1010 | <date> | 242.22.21.33 |
-------------
|1010 | <date> | 256.22.21.33 |
-------------

so from this table i would to a
SELECT DISTINCT client_id from history (if thats the syntax) this would
return
----
|client_id |
----
|1010 |
----
|1818 |
----
|1542 |
----

Now from these values i want do a
SELECT count(DISTINCT source) from history where client_id = 1010

this would return 4. Since client_id 1010 logged in from 4 different
sources.
Then i want to run the same query with client_id = 1818 and so on. I.e
loop through the client ids.

How can i do this in a stored proc. My guess is cursors. Any help?

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Don't just participate in USENET...get rewarded for it!|||No need for cursors or loops. This should give the result you want:

SELECT client_id, COUNT(DISTINCT source)
FROM History
GROUP BY client_id

--
David Portas
SQL Server MVP
--|||
Dave, you're a champ!

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