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geoinf16:sqlcartodb
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| Both sides previous revision Previous revision Next revision | Previous revision | ||
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geoinf16:sqlcartodb [2016/11/25 08:16] oertz |
geoinf16:sqlcartodb [2018/05/16 10:05] (current) |
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| * A vous de jouer en donnant de bonnes infos | * A vous de jouer en donnant de bonnes infos | ||
| <code> | <code> | ||
| - | INSERT INTO earthquakes (place, mag, the_geom) VALUES ('SOMEWHERE, Switzerland', MMM, ST_Transform(ST_GeometryFromText('POINT(XXX YYY)', 21781), 4326)); | + | INSERT INTO earthquakes (place, mag, the_geom) |
| + | VALUES ('SOMEWHERE, Switzerland', MMM, ST_Transform(ST_GeometryFromText('POINT(XXX YYY)', 21781), 4326)); | ||
| </code> | </code> | ||
| Line 29: | Line 30: | ||
| * Exercice ST_Distance (1) : quelle distance sépare chaque séisme de Fukushima - POINT(141.0357 37.4217) ? | * Exercice ST_Distance (1) : quelle distance sépare chaque séisme de Fukushima - POINT(141.0357 37.4217) ? | ||
| <code> | <code> | ||
| - | ... | + | SELECT *, |
| + | ST_Distance( | ||
| + | the_geom::geography, | ||
| + | ST_GeometryFromText('POINT(141.0357 37.4217)',4326)::geography | ||
| + | ) / 1000 as d FROM earthquakes | ||
| </code> | </code> | ||
| - | * Adapter le style (plus on s'éloigne de Fukushima, plus la couleur du point représenté s'éclaircie) | ||
| * Exercice ST_Distance (2) : quel est le séisme de magnitude > 6 le plus proche de Fukushima ? | * Exercice ST_Distance (2) : quel est le séisme de magnitude > 6 le plus proche de Fukushima ? | ||
| + | <code> | ||
| + | SELECT *, | ||
| + | ST_Distance( | ||
| + | the_geom::geography, | ||
| + | ST_GeometryFromText('POINT(141.0357 37.4217)',4326)::geography | ||
| + | ) / 1000 as d FROM earthquakes WHERE mag > 6 ORDER BY d LIMIT 1 | ||
| + | </code> | ||
| + | * Il serait souhaitable d'opter pour une autre approche que ce gourmand ORDER BY. Comment ? | ||
| + | <code> | ||
| + | ... | ||
| + | </code> | ||
| ===== Partie 2 ===== | ===== Partie 2 ===== | ||
| Line 53: | Line 68: | ||
| </code> | </code> | ||
| * Comme on sait comment cette zone est configurée, on peut aussi utiliser simplement ST_Distance, voire ST_DWithin http://postgis.net/docs/manual-2.3/ST_DWithin.html | * Comme on sait comment cette zone est configurée, on peut aussi utiliser simplement ST_Distance, voire ST_DWithin http://postgis.net/docs/manual-2.3/ST_DWithin.html | ||
| + | <code> | ||
| + | ... | ||
| + | </code> | ||
| + | |||
geoinf16/sqlcartodb.1480058200.txt.gz · Last modified: 2018/05/16 10:05 (external edit)
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