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POPostgresql / PostGIS, calculating a running total until a certain amount while ordering on calculated column
 

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  1. POPostgresql / PostGIS, calculating a running total until a certain amount while ordering on calculated column
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    <p>I have a query very similar to <a href="https://stackoverflow.com/questions/10549327/postgresql-select-until-certain-total-amount-is-reached" title="this one">this question</a> where I'm creating a running total until I reach a certain value. In my case, I'm counting population of counties until I reach the desired population. </p> <p>I want to order the search by the distance to a lng/lat, however, so that I add counties that are closest first. I'm running this query below but I get no results. When I instead do <code>ORDER BY row_id</code> or any non-SPATIALLY-calculated column, it comes back with results. I've also tried it using two <code>WITH</code> clauses but I still get no results. I've tried casting <code>distance</code> as integer since maybe it wasn't typed properly but that didn't help.</p> <p>I've set up a test server where you can run queries with this endpoint <code>http://sqltestmcr.cartodb.com/api/v2/sql?q=&lt;your query statement here&gt;</code></p> <p>This is the query that I am trying. Below are variations that work. You can see the results of this query with this link: <code>http://sqltestmcr.cartodb.com/api/v2/sql?q=SELECT%20*%20FROM%20(%20SELECT%20county,%20the_geom,%20distance,%20row_id_2,%20sum(population)%20over%20(order%20by%20distance%20asc)%20as%20running_total%20FROM%20(%20SELECT%20row_id,%20county,%20population,%20the_geom,%20row_id%20*%202%20AS%20row_id_2,%20ST_Distance(%20ST_Centroid(the_geom),%20ST_GeomFromText('POINT(-72.1235%2042.3521)',%204326)%20)%20AS%20distance%20FROM%20counties_ny_export)%20sq1)%20sq2%20WHERE%20running_total%20%3C=%201400</code></p> <pre><code> SELECT * FROM ( SELECT county, the_geom, distance, row_id_2, sum(population) over (order by distance asc) as running_total FROM ( SELECT row_id, county, population, the_geom, row_id * 2 AS row_id_2, ST_Distance( ST_Centroid(the_geom), ST_GeomFromText('POINT(-72.1235 42.3521)', 4326) ) AS distance FROM counties_ny_export ) sq1 ) sq2 where running_total &lt;= 1400 </code></pre> <p>The following two queries works where I set <code>ORDER BY row_id</code> or <code>ORDER BY row_id_2</code> Test link with <code>row_id</code>: <code>http://sqltestmcr.cartodb.com/api/v2/sql?q=SELECT%20*%20FROM%20(%20SELECT%20county,%20the_geom,%20distance,%20row_id_2,%20sum(population)%20over%20(order%20by%20row_id%20asc)%20as%20running_total%20FROM%20(%20SELECT%20row_id,%20county,%20population,%20the_geom,%20row_id%20*%202%20AS%20row_id_2,%20ST_Distance(%20ST_Centroid(the_geom),%20ST_GeomFromText('POINT(-72.1235%2042.3521)',%204326)%20)%20AS%20distance%20FROM%20counties_ny_export)%20sq1)%20sq2%20WHERE%20running_total%20%3C=%201400</code></p> <pre><code> SELECT * FROM ( SELECT county, the_geom, distance, row_id_2, sum(population) over (order by row_id asc) as running_total FROM ( SELECT row_id, county, population, the_geom, row_id * 2 AS row_id_2, ST_Distance( ST_Centroid(the_geom), ST_GeomFromText('POINT(-72.1235 42.3521)', 4326) ) AS distance FROM counties_ny_export ) sq1 ) sq2 where running_total &lt;= 1400 </code></pre> <p>Test link with <code>row_id_2</code>: <code>http://sqltestmcr.cartodb.com/api/v2/sql?q=SELECT%20*%20FROM%20(%20SELECT%20county,%20the_geom,%20distance,%20row_id_2,%20sum(population)%20over%20(order%20by%20row_id_2%20asc)%20as%20running_total%20FROM%20(%20SELECT%20row_id,%20county,%20population,%20the_geom,%20row_id%20*%202%20AS%20row_id_2,%20ST_Distance(%20ST_Centroid(the_geom),%20ST_GeomFromText('POINT(-72.1235%2042.3521)',%204326)%20)%20AS%20distance%20FROM%20counties_ny_export)%20sq1)%20sq2%20WHERE%20running_total%20%3C=%201400</code></p>
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    1. USCommunity
    1. USmhkeller
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    1. COIf you can provide some sample on [SQLFiddel](http://sqlfiddle.com/#!1) then it will be much easier to solve your problem
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      1. POPostgresql / PostGIS, calculating a running total until a certain amount while ordering on calculated column
      1. USRomesh
    2. COSQL Fiddle doesn't have PostGIS capabilities and PostGIS seems to be the problem since other, non-spatially-computed column values work. Instead, I've created a test database you can query through the endpoints above. You can see the full data with `http://sqltestmcr.cartodb.com/api/v2/sql?q=SELECT * FROM counties_ny_export`. Queries needn't be URI-encoded.
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      1. POPostgresql / PostGIS, calculating a running total until a certain amount while ordering on calculated column
      1. USmhkeller
 

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