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Thanks for your feedback, Darrel! I hope, your query results will
look fine.<br>
<br>
Regards,<br>
<br>
Birgit<br>
<br>
<br>
<div class="moz-cite-prefix">Am 24.11.2015 um 14:00 schrieb Darrel
Maddy:<br>
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<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US">Dear
Birgit,<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US">Very many
thanks. The query is now running – so it is no longer giving
an error. I will not know for a few hours whether it is
calculating the necessary values but it seems progress is
being made.<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US">I have a
book coming on SQL – I clearly need to do my homework more
thoroughly
</span><span
style="font-family:Wingdings;color:#1F497D;mso-fareast-language:EN-US">J</span><span
style="color:#1F497D;mso-fareast-language:EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US">I will
confirm when it stops!<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US">Best wishes<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US">Darrel<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="color:windowtext"
lang="EN-US">From:</span></b><span
style="color:windowtext" lang="EN-US"> postgis-users
[<a class="moz-txt-link-freetext" href="mailto:postgis-users-bounces@lists.osgeo.org">mailto:postgis-users-bounces@lists.osgeo.org</a>]
<b>On Behalf Of </b>Birgit Laggner<br>
<b>Sent:</b> 24 November 2015 12:19<br>
<b>To:</b> <a class="moz-txt-link-abbreviated" href="mailto:postgis-users@lists.osgeo.org">postgis-users@lists.osgeo.org</a><br>
<b>Subject:</b> Re: [postgis-users] Help with SQL query?<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal" style="margin-bottom:12.0pt">Hi Darrel,<br>
<br>
my PostGIS version is too old for testing, but if I read the
documentation right, then your expression has to be SQL. And
IF THEN ELSE etc. is not SQL as far as I know - SQL has CASE
WHEN.<br>
<br>
So, I would assume, you would need to write your expression
like this:<br>
<br>
'CASE WHEN [rast2] > 0.0 THEN [rast1] ELSE NULL END'<br>
<br>
I am curious if this helps with your error...<br>
<br>
Regards,<br>
<br>
Birgit<br>
<br>
<span style="font-size:12.0pt"><o:p></o:p></span></p>
<div>
<p class="MsoNormal">Am 24.11.2015 um 10:09 schrieb Darrel
Maddy:<o:p></o:p></p>
</div>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US">Dear
Roxanne,</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US">Many
thanks. I did pickup that issue shortly after my last post
and it cured the first problem.</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US">There is
still an SQL issue with the expression however.</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US">I tried
‘IF [rast2]>0.0 THEN [rast1] ELSE NULL ENDIF’</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US">This
produces an error at $2. I can remove that problem by
doing this</span><o:p></o:p></p>
<p class="MsoNormal"><a moz-do-not-send="true"
name="_MailEndCompose"><span
style="color:#1F497D;mso-fareast-language:EN-US">‘IF
([rast2]>0.0) THEN [rast1] ELSE NULL ENDIF’</span></a><o:p></o:p></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US">But then
I get the error at THEN</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US">Curiously
‘[rast2]+[rast1]’ works as intended so somehow the
conditional is being specified incorrectly.</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US">Unfortunately
there is nothing in the documentation which helps me with
this variant.
</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US">I will
keep trying.</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US">Darrel</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US"> </span><o:p></o:p></p>
<div>
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<p class="MsoNormal"><b><span style="color:windowtext"
lang="EN-US">From:</span></b><span
style="color:windowtext" lang="EN-US"> postgis-users [<a
moz-do-not-send="true"
href="mailto:postgis-users-bounces@lists.osgeo.org">mailto:postgis-users-bounces@lists.osgeo.org</a>]
<b>On Behalf Of </b>Roxanne Reid-Bennett<br>
<b>Sent:</b> 24 November, 2015 12:46 AM<br>
<b>To:</b> <a moz-do-not-send="true"
href="mailto:postgis-users@lists.osgeo.org">postgis-users@lists.osgeo.org</a><br>
<b>Subject:</b> Re: [postgis-users] Help with SQL
query?</span><o:p></o:p></p>
</div>
</div>
<p class="MsoNormal"> <o:p></o:p></p>
<div>
<p class="MsoNormal">On 11/23/2015 12:41 PM, Darrel Maddy
wrote:<o:p></o:p></p>
</div>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US">Dear
Pierre,</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US">I was
not looking for a total solution and I am grateful for
the suggestion.
</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US">Although
it may not look like it, I did consult the documentation
and also I have Regina’s book beside me. Unfortunately,
for me at least, both documents assume some knowledge of
SQL – which I do not have. I am also trying to do this
simultaneously with a large number of other things that
are new to me. I do not find the errors reported at all
informative and consider the query I am trying to
perform to be relatively trivial and hence I had hoped
the structure of the query might have been more
intuitive. For others it may be.</span><o:p></o:p></p>
</blockquote>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Times New Roman
,serif",serif"><br>
FWIW - I don't play with rasters, but this appears to be a
pure SQL thing... add "as rast" like below and try again.<br>
<br>
<br>
</span><span style="font-size:12.0pt">SELECT
ST_MapAlgebra(deposition.rast, concentrated.rast, 'IF
concentrated > 6 THEN deposition ELSE NULL ENDIF ' )
<br>
</span><span style="font-size:12.0pt;font-family:"Times
New Roman ,serif",serif">as rast</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">
FROM mymodel.deposition, mymodel.concentrated</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">
WHERE ST_UpperleftX(mymodel.deposition.rast) =
ST_UpperleftX(mymodel.concentrated.rast) AND
</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> ST_UpperleftY(mymodel.deposition.rast)
= ST_UpperleftY(mymodel.deposition.rast)</span><o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">Roxanne<o:p></o:p></p>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Times New Roman
,serif",serif"><br>
<br>
<br>
</span><o:p></o:p></p>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US">I will
try not to bother you again.</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US">Darrel</span><o:p></o:p></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span
style="color:#1F497D;mso-fareast-language:EN-US"> </span><o:p></o:p></p>
<div>
<div style="border:none;border-top:solid #E1E1E1
1.0pt;padding:3.0pt 0cm 0cm 0cm">
<p class="MsoNormal"><b><span lang="EN-US">From:</span></b><span
lang="EN-US"> postgis-users [<a
moz-do-not-send="true"
href="mailto:postgis-users-bounces@lists.osgeo.org">mailto:postgis-users-bounces@lists.osgeo.org</a>]
<b>On Behalf Of </b>Pierre Racine<br>
<b>Sent:</b> 23 November 2015 20:30<br>
<b>To:</b> PostGIS Users Discussion <a
moz-do-not-send="true"
href="mailto:postgis-users@lists.osgeo.org">
<postgis-users@lists.osgeo.org></a><br>
<b>Subject:</b> Re: [postgis-users] Help with SQL
query?</span><o:p></o:p></p>
</div>
</div>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"
lang="EN-US">The expression has to stay as it was: 'IF
[rast2] > threshold THEN [rast1] ELSE NULL ENDIF '</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"
lang="EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"
lang="EN-US">Just replace the threshold value as you
did.</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"
lang="EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"
lang="EN-US">Do not try to replace the [rast2] and
[rast1]. They refer to the first and second raster pixel
values. Read the ST_Mapalgebra doc…</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"
lang="EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"
lang="EN-US">Don’t expect our suggestions to work
blindly. I did not test this query. I’m not in your
context. I expect you read the doc about all the
mentioned functions and adjust for your specific
context. I said “your query should “look like” this”…</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"
lang="EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"
lang="EN-US">Pierre</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"
lang="EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"
lang="EN-US"> </span><o:p></o:p></p>
<div style="border:none;border-left:solid blue
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<div>
<div style="border:none;border-top:solid #B5C4DF
1.0pt;padding:3.0pt 0cm 0cm 0cm">
<p class="MsoNormal"><b><span
style="font-size:10.0pt;font-family:"Tahoma",sans-serif"
lang="EN-US">From:</span></b><span
style="font-size:10.0pt;font-family:"Tahoma",sans-serif"
lang="EN-US"> postgis-users [<a
moz-do-not-send="true"
href="mailto:postgis-users-bounces@lists.osgeo.org">mailto:postgis-users-bounces@lists.osgeo.org</a>]
<b>On Behalf Of </b>Darrel Maddy<br>
<b>Sent:</b> Monday, November 23, 2015 2:47 PM<br>
<b>To:</b> PostGIS Users Discussion<br>
<b>Subject:</b> Re: [postgis-users] Help with SQL
query?</span><o:p></o:p></p>
</div>
</div>
<p class="MsoNormal"><span lang="EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">OK I
spoke too soon.</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">I tried
this:</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">SELECT
(ST_SummaryStats(ST_Union(rast))).sum sum</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">FROM
(SELECT ST_MapAlgebra(deposition.rast,
concentrated.rast, 'IF concentrated > 6 THEN
deposition ELSE NULL ENDIF ' )</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">
FROM mymodel.deposition, mymodel.concentrated</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">
WHERE ST_UpperleftX(mymodel.deposition.rast) =
ST_UpperleftX(mymodel.concentrated.rast) AND
</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> ST_UpperleftY(mymodel.deposition.rast)
= ST_UpperleftY(mymodel.deposition.rast) ) foo;</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">And all I
get is rast does not exist.</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">I’m
afraid the penny has not dropped yet
</span><span style="font-family:Wingdings;color:#1F497D">L</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">Darrel</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></p>
<div>
<div style="border:none;border-top:solid #E1E1E1
1.0pt;padding:3.0pt 0cm 0cm 0cm">
<p class="MsoNormal"><b><span lang="EN-US">From:</span></b><span
lang="EN-US"> postgis-users [<a
moz-do-not-send="true"
href="mailto:postgis-users-bounces@lists.osgeo.org">mailto:postgis-users-bounces@lists.osgeo.org</a>]
<b>On Behalf Of </b>Darrel Maddy<br>
<b>Sent:</b> 23 November 2015 16:30<br>
<b>To:</b> PostGIS Users Discussion <<a
moz-do-not-send="true"
href="mailto:postgis-users@lists.osgeo.org">postgis-users@lists.osgeo.org</a>><br>
<b>Subject:</b> Re: [postgis-users] Help with SQL
query?</span><o:p></o:p></p>
</div>
</div>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">Dear
Pierre and Rasmus,</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">Many
thanks for trying to help.</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">Rasmus: I
am aware of GMT but I was looking for a solution in
postgis so that I can keep all of the data extraction
in one place.</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">Pierre:
That is exactly what I was looking for and very many
thanks for including the explanation. I am a little
overwhelmed with the number of functions offered in
postgis. It is certainly a remarkable tool. Watching
the queries plough through my datasets is a pleasure –
albeit the results do not always please me
</span><span style="font-family:Wingdings;color:#1F497D">J</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">Hopefully
I can put this to work later tonight.</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">Best
wishes</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D">Darrel</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"> </span><o:p></o:p></p>
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<p class="MsoNormal"><b><span lang="EN-US">From:</span></b><span
lang="EN-US"> postgis-users [<a
moz-do-not-send="true"
href="mailto:postgis-users-bounces@lists.osgeo.org">mailto:postgis-users-bounces@lists.osgeo.org</a>]
<b>On Behalf Of </b>Pierre Racine<br>
<b>Sent:</b> 23 November 2015 16:17<br>
<b>To:</b> PostGIS Users Discussion <<a
moz-do-not-send="true"
href="mailto:postgis-users@lists.osgeo.org">postgis-users@lists.osgeo.org</a>><br>
<b>Subject:</b> Re: [postgis-users] Help with SQL
query?</span><o:p></o:p></p>
</div>
</div>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"
lang="EN-US">Darrel,</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"
lang="EN-US"> </span><o:p></o:p></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt"><span
style="color:#1F497D" lang="EN-US">1)</span><span
style="font-size:7.0pt" lang="EN-US">
</span><span style="color:#1F497D" lang="EN-US">Create a
new raster selecting the right pixels with
ST_MapAlgebra(raster, raster)</span><o:p></o:p></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt"><span
style="color:#1F497D" lang="EN-US">2)</span><span
style="font-size:7.0pt" lang="EN-US">
</span><span style="color:#1F497D" lang="EN-US">Make
sure only intersecting rasters are processed by using
their upper left corner X and Y coordinates (with
ST_UpperLeftX() and UpperLeftY())</span><o:p></o:p></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt"><span
style="color:#1F497D" lang="EN-US">3)</span><span
style="font-size:7.0pt" lang="EN-US">
</span><span style="color:#1F497D" lang="EN-US">Sum the
selected pixels with ST_SummaryStats(rast)</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"
lang="EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"
lang="EN-US">All in all a global query should look
like this:</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"
lang="EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"
lang="EN-US">SELECT
(ST_SummaryStats(ST_Union(rast))).sum sum</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"
lang="EN-US">FFOM (SELECT ST_MapAlgebra(tableA.rast,
tableB.rast, 'IF [rast2] > threshold THEN [rast1]
ELSE NULL</span><span lang="EN-US"> ENDIF
</span><span style="color:#1F497D" lang="EN-US">' )</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"
lang="EN-US"> FROM tableA, tableB</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"
lang="EN-US"> WHERE
ST_UpperleftX(tableA.rast) =
ST_UpperleftX(tableB.rast) AND
</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"
lang="EN-US"> ST_UpperleftY(tableA.rast)
= ST_UpperleftY(tableB.rast) AND
</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"
lang="EN-US"> maybe some other
condition here if you get time series e.g. tableA.year
= tableB.year AND tableA.month = tableB.month) foo</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"
lang="EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"
lang="EN-US">If you have millions of tile you could
create indexes on ST_UpperleftX(tableA.rast),
ST_UpperleftX(tableB.rast), ST_UpperleftY(tableA.rast)
and ST_UpperleftY(tableB.rast) to make the query
faster.</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"
lang="EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"
lang="EN-US">You could also just use WHERE
ST_Intersects(tableA.rast, tableB.rast) instead…</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"
lang="EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"
lang="EN-US">Pierre</span><o:p></o:p></p>
<p class="MsoNormal"><span style="color:#1F497D"
lang="EN-US"> </span><o:p></o:p></p>
<div style="border:none;border-left:solid blue
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<p class="MsoNormal"><b><span
style="font-size:10.0pt;font-family:"Tahoma",sans-serif"
lang="EN-US">From:</span></b><span
style="font-size:10.0pt;font-family:"Tahoma",sans-serif"
lang="EN-US"> postgis-users [<a
moz-do-not-send="true"
href="mailto:postgis-users-bounces@lists.osgeo.org">mailto:postgis-users-bounces@lists.osgeo.org</a>]
<b>On Behalf Of </b>Darrel Maddy<br>
<b>Sent:</b> Monday, November 23, 2015 7:20 AM<br>
<b>To:</b> PostGIS Users Discussion<br>
<b>Subject:</b> [postgis-users] Help with SQL
query?</span><o:p></o:p></p>
</div>
</div>
<p class="MsoNormal"><span lang="EN-US"> </span><o:p></o:p></p>
<p class="MsoNormal">Dear all,<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">As you know I am relatively new to
postgis and SQL and therefore I have much to learn.
However, I am facing a paper deadline and need to do
some quick analysis of the data I have and I am
struggling to figure out how best to pursue what I
need to do.<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">I have a significant number of
rasters which have double precision values. Without
going into detail about what the rasters represent, I
need to extract and sum values from one set of rasters
in say table A based upon values in another set of
rasters in say table B where the pixel value in the
raster from Table B exceeds a threshold. Both tables
are the same size (rasters are tiled) but I also need
to figure out how I make sure the correct rasters are
compared. They have filenames like this
rastervariable_10.tif, rastervariable_100.tif ,
presumably I need to use a logical expression to strip
the numerical value (in this case this represents the
year) and then order on that basis?<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">I can do this in QGIS one at a time
but that is a little clumsy and rather time consuming.
<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">If someone can just point me in the
right direction I am sure I can figure out the rest
for myself.<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">Apologies once more for asking what
is probably a rather trivial question and yet again
demonstrating my ignorance.<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">Many thanks<o:p></o:p></p>
<p class="MsoNormal"> <o:p></o:p></p>
<p class="MsoNormal">Darrel<o:p></o:p></p>
</div>
</div>
<p class="MsoNormal"><span
style="font-size:12.0pt;font-family:"Times New
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<pre>-- <o:p></o:p></pre>
<pre>[At other schools] I think the most common fault in general is to teach students how to pass exams instead of teaching them the science.<o:p></o:p></pre>
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