[postgis-users] Populating Multipolygon Z as calculation

[Chris English]

Hello,

I've been wrestling around with 3D and have gotten my table/geom to x,y,z
so that

SELECT ST_AsEwkt(the_geom) FROM <table>
LIMIT 1;

returns
"MULTIPOLYGON(((611630.148961496 690526.520745486 0,611619.960661661
690507.134957485 0,
611545.79119058 690545.364867903 0,611556.435198162 690565.595798574
0,611630.148961496 690526.520745486 0)))"

In another column are the values I'd like to use for Z, or calculate  Z
from.

And then brain death.  What sort of statement would I be using to update the
Z part of the XYZ,  as a calculated result
from another column.

Any help or suggestions greatly appreciated.

Chris
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