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SQL - query to remove ID that has been contacted

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Last Modified: 2014-05-19
I have a table in a SQL database that stores the number of times a client is contacted.

It looks similar to this:

ID           Date               Status
1001       2014-05-01     Not Contacted
1001       2014-05-02     Not Contacted
1001       2014-05-04     Contacted
1005       2014-05-04     Not Contacted
1005       2014-05-05     Contacted
1007       2014-05-07     Not Contacted
1007       2014-05-08     Not Contacted
1009       2014-05-08     Not contacted

I want to select only those ID's that have not been contacted, so if you look at my example. ID 1001 has been attempted 3 times. but since t has been contacted, I want to exclude it.  ID 1007 and 1009 have not been contacted so those are the only 2 I want to return.  Any ideas on how to do this?
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Commented:
This one is on us!
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PortletPaulEE Topic Advisor
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Commented:
A more efficient approach requiring just a single pass of the data is like this
SELECT
        id
FROM Contacts
GROUP BY
      id
HAVING
      count(CASE WHEN Status = 'Contacted' THEN 1 END) = 0
;

--result
|   ID |
|------|
| 1007 |
| 1009 |
	

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Commented:
@PortletPaul: what if they need to retrieve other columns alongside with id
PortletPaulEE Topic Advisor
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Commented:
>>from the question: "I want to select only those ID's that have not been contacted"
extra columns aren't requested, and probably not needed

Let's assume I haven't contacted you for the last month; do I really need 28/29/30 or 31 records to tell me I haven't contacted you? :-)

The group by approach could return min(date)/max(date) which might be useful (perhaps)
PortletPaulEE Topic Advisor
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Commented:
Oh well it appears the debate is academic.

@Jasmin01 if you do only want the ID, then my suggestion is more efficient (faster)

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