Length

The function "Length" allows to determine the length of objects which are present in a table, via the field "the_geom".

Syntax : select ST_Length(the_geom) from myTable; |

Example :

- Goal : Calculate the sum of the lengthes of the hydrographic sections

- Syntax : select Sum(ST_Length(the_geom)) as Longueur from "TRONCON_HYDROGRAPHIQUE";

- Result : we obtain an alphanumeric value

Remarks :

- The first operator Length calculate the length of every geometry. The identifier the_geom corresponds to the column which contains the geometry of objects. Note that this identifier is necessary for all spatial functions.

- The second operator Sum is an aggregated alphanumeric function which calculate the global length - > the total - > the sum.

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