<div dir="ltr"><div><div>Outra solução é usar Views.<br><br></div>Cria uma View que faça os calculos e depois em vez de fazeres SELECT à tabela, fazes SELECT à View.<br><br>Na definição da View:<br><br>SELECT ST_AREA(geom)/10000 as areahectares FROM Parcela;<br><br></div>Através do PgAdmin é facil criar uma View.<br><br></div><div class="gmail_extra"><br><div class="gmail_quote">No dia 2 de abril de 2015 às 12:15, Nuno Cortês <span dir="ltr"><<a href="mailto:nmrcortes@live.com.pt" target="_blank">nmrcortes@live.com.pt</a>></span> escreveu:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<div dir="ltr" style="font-family:'Calibri','Segoe UI','Meiryo','Microsoft YaHei UI','Microsoft JhengHei UI','Malgun Gothic','sans-serif';font-size:12pt"><div>Obrigado a Todos</div><div><br></div><div>Já esta a funcionar.</div><div><br></div><div>Abraço</div><div>Nuno Cortês<br></div><div><div><br></div><div>Enviado de Correio do Windows</div><div><br></div></div><div style="padding-top:5px;border-top-color:rgb(229,229,229);border-top-width:1px;border-top-style:solid"><div><font style="line-height:15pt;letter-spacing:0.02em;font-family:"Calibri","Segoe UI","Meiryo","Microsoft YaHei UI","Microsoft JhengHei UI","Malgun Gothic","sans-serif";font-size:12pt" face=" 'Calibri', 'Segoe UI', 'Meiryo', 'Microsoft YaHei UI', 'Microsoft JhengHei UI', 'Malgun Gothic', 'sans-serif'"><b>De:</b> <a href="mailto:andre.s.mano@gmail.com" target="_blank">Andre Mano</a><br><b>Enviada:</b> quinta-feira, 2 de abril de 2015 09:58<br><b>Para:</b> <a href="mailto:portugal@lists.osgeo.org" target="_blank">portugal@lists.osgeo.org</a></font></div></div><div><div class="h5"><div><br></div><div dir=""><div dir="ltr"><div><div>Ola Marco,<br><br></div>Para fazeres isso tens de implementar um trigger na tua base de dados. Estes comandos deverao funcionar, apenas tens de mudar o nome dos campos:<br><font><br>
</font><p style="text-align:left;margin-top:0pt;margin-bottom:0pt;vertical-align:baseline;direction:ltr"><font><span style="color:rgb(0,176,80);font-family:Arial">-- Cr</span><span style="color:rgb(0,176,80);font-family:Arial">iar o trigger<br></span></font></p><font>
</font><p style="text-align:left;margin-top:0pt;margin-bottom:0pt;vertical-align:baseline;direction:ltr"><font><span style="color:blue;font-family:Arial">CREATE </span><span style="color:blue;font-family:Arial">OR REPLACE FUNCTION </span><span style="color:black;font-family:Arial">computing_area</span><span style="color:black;font-family:Arial">()<span>
</span></span><span style="color:black;font-family:Arial"><span> </span></span></font></p><font>
</font><p style="text-align:left;margin-top:0pt;margin-bottom:0pt;vertical-align:baseline;direction:ltr"><font><span style="color:blue;font-family:Arial"><span> </span>RETURNS
</span><span style="color:blue;font-family:Arial">TRIGGER </span><span style="color:blue;font-family:Arial">AS</span></font></p><font>
</font><p style="text-align:left;margin-top:0pt;margin-bottom:0pt;vertical-align:baseline;direction:ltr"><font><span style="color:black;font-family:Arial"><span>
</span>$</span><span style="color:blue;font-family:Arial">BODY</span><span style="color:black;font-family:Arial">$</span><span style="color:blue;font-family:Arial"><span>
</span></span></font></p><font>
</font><p style="text-align:left;margin-top:0pt;margin-bottom:0pt;vertical-align:baseline;direction:ltr"><font><span style="color:blue;font-family:Arial"><span> </span></span><span style="color:blue;font-family:Arial">BEGIN<span> </span></span></font></p><font>
</font><p style="text-align:left;margin-top:0pt;margin-bottom:0pt;vertical-align:baseline;direction:ltr"><font><span style="color:blue;font-family:Arial"><span> </span><span> </span></span><span style="color:blue;font-family:Arial"><span> </span></span><span style="color:blue;font-family:Arial">NEW.area</span><span style="color:blue;font-family:Arial"> </span><span style="color:blue;font-family:Arial">:=
ROUND((</span><span style="color:blue;font-family:Arial">st_area</span><span style="color:blue;font-family:Arial">(</span><span style="color:blue;font-family:Arial">NEW.geom</span><span style="color:blue;font-family:Arial">))::numeric,2);<span> </span><span> </span></span><span style="color:blue;font-family:Arial"><span> </span>RETURN </span><span style="color:blue;font-family:Arial">NEW;<span> </span></span></font></p><font>
</font><p style="text-align:left;margin-top:0pt;margin-bottom:0pt;vertical-align:baseline;direction:ltr"><font><span style="color:blue;font-family:Arial"><span> </span></span><span style="color:blue;font-family:Arial">END;</span></font></p><font>
</font><p style="text-align:left;margin-top:0pt;margin-bottom:0pt;vertical-align:baseline;direction:ltr"><font><span style="color:black;font-family:Arial"><span>
</span>$</span><span style="color:blue;font-family:Arial">BODY</span><span style="color:black;font-family:Arial">$</span><span style="color:blue;font-family:Arial"><span>
</span></span></font></p><font>
</font><p style="text-align:left;margin-top:0pt;margin-bottom:0pt;vertical-align:baseline;direction:ltr"><font><span style="color:blue;font-family:Arial">LANGUAGE </span><span style="color:black;font-family:Arial">'</span><span style="color:black;font-family:Arial">plpgsql</span><span style="color:black;font-family:Arial">'</span></font></p><p style="text-align:left;margin-top:0pt;margin-bottom:0pt;vertical-align:baseline;direction:ltr"><font><span style="color:black;font-family:Arial"><br></span></font></p><font>
</font><p style="text-align:left;margin-top:0pt;margin-bottom:0pt;vertical-align:baseline;direction:ltr"><font><span style="color:rgb(0,176,80);font-family:Arial">-- </span><span style="color:rgb(0,176,80);font-family:Arial">implementar o trigger<br></span></font></p><font>
</font><p style="text-align:left;margin-top:0pt;margin-bottom:0pt;vertical-align:baseline;direction:ltr"><font><span style="color:blue;font-family:Arial">CREATE TRIGGER</span><span style="color:black;font-family:Arial"> </span><span style="color:black;font-family:Arial">calculate_area</span><span style="color:black;font-family:Arial"> </span></font></p><font>
</font><p style="text-align:left;margin-top:0pt;margin-bottom:0pt;vertical-align:baseline;direction:ltr"><font><span style="color:blue;font-family:Arial"><span> </span>BEFORE</span><span style="color:black;font-family:Arial"> </span><span style="color:blue;font-family:Arial">INSERT</span><span style="color:black;font-family:Arial"> </span><span style="color:blue;font-family:Arial">OR</span><span style="color:black;font-family:Arial"> </span><span style="color:blue;font-family:Arial">UPDATE<span> </span></span></font></p><font>
</font><p style="text-align:left;margin-top:0pt;margin-bottom:0pt;vertical-align:baseline;direction:ltr"><font><span style="color:blue;font-family:Arial"><span> </span>ON</span><span style="color:black;font-family:Arial"> </span><span style="color:black;font-family:Arial">landplot</span><span style="color:black;font-family:Arial"><span> </span></span></font></p><font>
</font><p style="text-align:left;margin-top:0pt;margin-bottom:0pt;vertical-align:baseline;direction:ltr"><font><span style="color:blue;font-family:Arial"><span> </span>FOR</span><span style="color:black;font-family:Arial"> </span><span style="color:blue;font-family:Arial">EACH</span><span style="color:black;font-family:Arial"> </span><span style="color:blue;font-family:Arial">ROW<span> </span></span></font></p><font>
</font><p style="text-align:left;margin-top:0pt;margin-bottom:0pt;vertical-align:baseline;direction:ltr"><font><span style="color:blue;font-family:Arial"><span> </span>EXECUTE</span><span style="color:black;font-family:Arial"> </span><span style="color:blue;font-family:Arial">PROCEDURE</span><span style="color:black;font-family:Arial"> </span><span style="color:black;font-family:Arial">computing_area</span><span style="color:black;font-family:Arial">();</span></font></p>
<br></div><br></div><div class="gmail_extra"><br><div class="gmail_quote">2015-04-02 10:47 GMT+02:00 <span dir="ltr"><<a href="mailto:nmrcortes@gmail.com" target="_blank">nmrcortes@gmail.com</a>></span>:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;padding-left:1ex;border-left-color:rgb(204,204,204);border-left-width:1px;border-left-style:solid">
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<div style="font-family:"Calibri","Segoe UI","Meiryo","Microsoft YaHei UI","Microsoft JhengHei UI","Malgun Gothic","sans-serif";font-size:12pt" dir="ltr"><div><br></div><div><div>Quero criar uma coluna numa tabela (polígono) no PostGIS que calcule a área automaticamente e que a mantenha actualizada sempre que se altere a geometria do polígono no Qgis.</div><div><br></div><div>Com o seguinte SQL:<br>UPDATE "Parcela" SET AreaHectares=ST_AREA(geom)/10000; <br>FROM<br> "Parcela"</div><div><br></div><div>Faz a actualização da área mas tenho que fazer o Update sempre que altero a geometria.<br>Há alguma forma de fazer isto automaticamente?</div><div><br></div><div>Obrigado<br>Nuno Cortês<br></div><div><br></div><div><br></div></div></div>
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<a href="http://lists.osgeo.org/mailman/listinfo/portugal" target="_blank">http://lists.osgeo.org/mailman/listinfo/portugal</a><br></blockquote></div><br><br clear="all"><br>-- <br><div class="gmail_signature"><div dir="ltr">Regards, <div>Marco Afonso</div><div><a href="http://goo.gl/ZDtQjm" target="_blank">http://goo.gl/ZDtQjm</a><br></div><div><span></span><img src="https://dl.dropboxusercontent.com/u/17607469/qr.png"><br></div></div></div>
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