ST_Length(VARCHAR(128)) method

Returns the length measurement of the ST_MultiCurve value. The result is measured in the units specified by the parameter.

Syntax

multicurve-expression.ST_Length(VARCHAR(128) unit_name)

unit_name – The units in which the length should be computed. Defaults to the unit of the spatial reference system. The unit name must match the UNIT_NAME column of a row in the ST_UNITS_OF_MEASURE view where UNIT_TYPE is 'LINEAR'.

DOUBLE Returns the length measurement of the ST_MultiCurve value.

Example 1 – The following example creates a multicurve and uses ST_Length to find the length of the geometry, returning the value PI+1.
```
SELECT NEW ST_MultiCurve(
NEW ST_LineString('LineString (0 0, 1 0)' ),
NEW ST_CircularString( 'CircularString( 0 0, 1 1, 2 0)' ) )
.ST_Length()
```
The following example returns the name and length of all roads longer than 100 miles. This example assumes the road table exists, that the geometry column has type ST_MultiCurve or ST_MultiLineString, and the sa_install_feature system procedure has been used to load the st_geometry_predefined_uom.
```
SELECT name, geometry.ST_Length( 'Statute Mile' ) len
FROM roads WHERE len > 100
```

SQL/MM (ISO/IEC 13249-3: 2006) 9.3.4