Retrieves the minimum M coordinate value of a geometry.
geometry-expression.ST_MMin()
DOUBLE Returns the minimum M coordinate value of the geometry-expression.
Returns the minimum M coordinate value of the geometry-expression. This is computed by comparing the M attribute of all points in the geometry.
If the geometry-expression is an empty geometry (ST_IsEmpty()=1), then this method returns NULL.
By default, ST_MMin uses the original format for a geometry, if it is available. Otherwise, the internal format is used. For more information about internal and original formats, see STORAGE FORMAT clause, CREATE SPATIAL REFERENCE SYSTEM statement.
SQL/MM (ISO/IEC 13249-3: 2006) Vendor extension
The following example returns the result 4.
4
SELECT NEW ST_LineString( 'LineString ZM( 1 2 3 4, 5 6 7 8 )' ).ST_MMin()