The SE_VertexUpdate() function
The SE_VertexUpdate() function changes the value of a vertex in a geometry. You must supply both the exact old value and the new value of the vertex to be altered. If the input geometry has Z values or measures, you must supply them as well. All vertices in the geometry which match the old value will be updated.
Syntax
SE_VertexUpdate (ST_Geometry, old ST_Point, new ST_Point)
Return type
ST_Geometry