[postgis-users] Generating Point geometry

[Robyn Rennie]

Hi all, 
I am new to PostGIS and I have installed it onto an existing PostgreSQL database. I have a table with an x and a y column and want to make a point geometry from these columns. 
I have done the following
SELECT AddGeometryColumn('table_xy_45700522','xypoint',-1,'POINT',1);
ALTER TABLE table_xy_45700522 DROP CONSTRAINT enforce_dims_xypoint;  - needed because it seemed to fail otherwise?
and now have a table which looks like samplename (varchar), x(float8), y(float8), xypoint(geometry). There are 800+ records in the table all with values in the samplename, x and y columns. How can I use MakePoint or some other function to get the geometry for each of these points?  (this is a test table - the real table has considerably more points)
Looking through the archives I only see references to loading the data from an external file.
Thanks for any assistance.
Robyn Rennie

 

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