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I have a point table and the buffer geometry is created around the point.

I have defined the if the point is within the buffer_distance then its value is =1 and if it is outside the buffer its value is =0, and when it is on buffer_polygon then =2.

Now when ever i change the location of point then it should check the following conditions and the flag value should change according to the location of point new position.

I am changing the position of the point in QGIS.

My table structure is like this:-

GID(PK) Flag(INT)   Buffer_Distance THE_Geom    Buffer_GEOM
1   1   100 point(X,Y Location) Buffer Created around the Point 
2   2   200 point(X,Y Location) Buffer Created around the Point 
3   2   200 point(X,Y Location) Buffer Created around the Point 
4   3   300 point(X,Y Location) Buffer Created around the Point 
5   3   300 point(X,Y Location) Buffer Created around the Point 
6   1   100 point(X,Y Location) Buffer Created around the Point 
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3 Answers 3

sir me have a point Table , in which the point geometry and the buffer geometry is created now if i move the point location in quantum gis then the values of the point should change.

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Please add this as a comment –  Nathan W Nov 27 '12 at 14:26
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Read about PostgreSQL Triggers. Real world example. You probably need after update or insert trigger.

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I'm unclear as to which point(s) are buffered and which ones might be moved in QGis but I think you need to define a trigger on your point table to run the query whenever a point is changed.

See if http://twiav-tt.blogspot.co.uk/2012/07/postgis-trigger-function-retrieve.html helps? Or this answer on StackOverflow?

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