Converting geometry of elements of table to move it from one srid system to another

Question

I have a table containing a column geom loaded from a shape file which was defined in lambert II system (27582), but when I loaded it I specified that I want to work in lambert 93 (2154).
Unfortunately when I load it in QGIS the coordinates are always in lambert II.
Is there a function allowing me to convert these coordinates and make them pass from lambert II (27582) to lambert 93 (2154)?
I would like to work only in lambert 93.

Ian Turton · Answer

Go back and repeat the load using EPSG:27582 or use ST_SetSRID to set the correct CRS - then use the ST_Transform function to convert them to be in EPSG:2154 if that is what you require.
UPDATE table SET geom = ST_Transform(ST_SetSRID(geom, 27582), 2154);

Though QGIS is quite capable of reprojecting on the fly for you once the correct SRID is set using just:
UPDATE table SET geom = ST_SetSRID(geom, 27582);

ramiroaznar · Answer

If your question is regarding PostGIS functions:
the ST_Transform function is what you are looking for. Something like this should do the trick:
UPDATE table
SET geom = ST_Transform(geom, 2154)

On the other hand, if your question is refering to a QGIS operation. You can change the SRID of your layer or the whole project from its properties.

Converting geometry of elements of table to move it from one srid system to another

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