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<p class="MsoNormal"><span lang="EN-US">HI,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">I’m trying to improve my current function to split polygons with lines.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">I have 2 layers, a polygon layer and a line layer.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">I Would like to punch out new polygons from a polygon layer using lines in a linelayer.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">I’ve tried this:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">CREATE TABLE split_polys_tmp AS<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">WITH RECURSIVE<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> split AS (<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> SELECT (SELECT MAX(fid) FROM linelayer) AS line_id<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> ST_Collect(a.the_geom) AS geom
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> FROM polygonlayer AS<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> UNION ALL<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> SELECT line_id - 1 AS line_id,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> ST_Split(c.geom, b.the_geom) AS geom<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> FROM split AS c,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> linelayer AS b<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> WHERE b.fid = c.line_id <o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> )<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">SELECT (ST_Dump(geom)).geom<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">FROM split<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">WHERE line_id = 0;<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">It works perfekt…<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">But the I would like an attribute (DMGS_ID) from polygonlayer (unique for each polygon) to be tranferred the splitted polygons in the new layer.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Then I tried this:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">CREATE TABLE split_polys_tmp AS<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">WITH RECURSIVE<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> split AS (<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> SELECT (SELECT MAX(fid) FROM rest) AS line_id, a."DMGS_UID",<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> ST_Collect(a.the_geom) AS geom
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> FROM polygonlayer AS a<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> UNION ALL<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> SELECT c."DMGS_UID" ,line_id - 1 AS line_id,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> ST_Split(c.geom, b.the_geom) AS geom<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> FROM split AS c,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> linelayer AS b<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> WHERE b.fid = c.line_id<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"> )<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">SELECT "DMGS_UID", (ST_Dump(geom)).geom<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">FROM split<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">WHERE line_id = 0;<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">It will not work. It seems like I have to add: GROUP BY "DMGS_UID" at the end of sql-line 5 and then the result (polygon) is different.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">How can I transfer an attribute from an original polygon to the new cutted polygons?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">If someone has the time and could take the effort to explain how to do this, I would be grateful.<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Kind regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">Paul<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:9.0pt;mso-fareast-language:SV"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US" style="font-size:9.0pt;mso-fareast-language:SV">
<o:p></o:p></span></p>
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