ST_YMax
Name
ST_YMax — Returns Y maxima of a bounding box 2d or 3d or a geometry.
Synopsis
    
     float
     
      ST_YMax
     
     (
    
    box3d
    
     aGeomorBox2DorBox3D
    
    
     )
    
    ;
   
Description
Returns Y maxima of a bounding box 2d or 3d or a geometry.
       
      | 
     |
| 
       Although this function is only defined for box3d, it will work for box2d and geometry because of the auto-casting behavior defined for geometries and box2d. However you can not feed it a geometry or box2d text representation, since that will not auto-cast.  | 
    
   
    
   
   This function supports 3d and will not drop the z-index.
  
   
    
   
   This method supports Circular Strings and Curves
  
Examples
SELECT ST_YMax('BOX3D(1 2 3, 4 5 6)');
st_ymax
-------
5
SELECT ST_YMax(ST_GeomFromText('LINESTRING(1 3 4, 5 6 7)'));
st_ymax
-------
6
SELECT ST_YMax(CAST('BOX(-3 2, 3 4)' As box2d));
st_ymax
-------
4
--Observe THIS DOES NOT WORK because it will try to autocast the string representation to a BOX3D
SELECT ST_YMax('LINESTRING(1 3, 5 6)');
--ERROR:  BOX3D parser - doesn't start with BOX3D(
SELECT ST_YMax(ST_GeomFromEWKT('CIRCULARSTRING(220268 150415 1,220227 150505 2,220227 150406 3)'));
st_ymax
--------
150506.126829327