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Michael Morris
#1 Posted : Monday, September 14, 2009 4:09:38 PM
Rank: Newbie
Groups: Member

Joined: 8/26/2009
Posts: 4
Location: Boston
Is it possible to execute a query using PI-OLEDB restricting the results to only those where the 'Annotations' field matches a particular pattern? For my data, I have a scale factor, an offset factor, and an optional QC flag for each observation of the form:

0.33,0.76,12222200000000

What I want to accomplish is to find the last observation that has a QC flag assigned to it (so the QC can start from that point). I am using the query:

Code:
select top 1 time from picomp2 where tag = 'poplar_greenwood_1_2151_2.0_P1_Avg' and annotations like '*,*,*' order by time desc


However, when I execute the query, I receive the following error message:

Code:

??? Invoke Error, Dispatch Exception:
Source: PIOLEDB
Description: Overload resolution failed for (LIKE) argument(s).


Thanks in advance for any help.
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RJK Solutions
#2 Posted : Tuesday, September 22, 2009 12:21:05 PM
Rank: Administration

Groups: Administration

Joined: 6/20/2008
Posts: 612
Location: Cheshire, United Kingdom.
Hi Michael,

To use the LIKE operator you need to compare against a string.
As annotations is a Variant, cast it as a string then use your LIKE pattern match.

Code:

select top 1 time from picomp2 where tag = 'poplar_greenwood_1_2151_2.0_P1_Avg' and CAST(annotations AS String) like '*,*,*' order by time desc


Cheers,

Rhys.
Principal Consultant
Real-Time Data Management @ Wipro Technologies
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