Definition
ST_M takes an ST_Point as an input parameter and returns its measure (m) coordinate.
In SQLite, ST_M can also be used to update a measure value.
Syntax
Oracle and PostgreSQL
sde.st_m (point1 sde.st_point)
SQLite
st_m (point1 geometryblob) st_m (point1 geometryblob, new_Mvalue double)
Return type
Oracle and PostgreSQL
Number
SQLite
Double precision if querying for a measure value; a geometryblob if updating a measure value
Examples
Oracle
The table, m_test, is created and three points inserted to it. All three contain measure values. A SELECT statement is run with the ST_M function to return the measure value for each point.
CREATE TABLE m_test (
id integer,
geometry sde.st_point);
INSERT INTO M_TEST VALUES (
1,
sde.st_point (2, 3, 32, 5, 4322)
);
INSERT INTO M_TEST VALUES (
2,
sde.st_point (4, 5, 20, 4, 4326)
);
INSERT INTO M_TEST VALUES (
3,
sde.st_point (3, 8, 23, 7, 4326)
);
SELECT id, sde.st_m (geometry) M_COORD
FROM M_TEST;
ID M_COORD
1 5
2 4
3 7
PostgreSQL
The table, m_test, is created and three points inserted to it. All three contain measure values. A SELECT statement is run with the ST_M function to return the measure value for each point.
CREATE TABLE m_test (
id serial,
geometry sde.st_point
);
INSERT INTO m_test (geometry) VALUES (
sde.st_point (2, 3, 32, 5, 4326)
);
INSERT INTO m_test (geometry) VALUES (
sde.st_point (4, 5, 20, 4, 4326)
);
INSERT INTO m_test (geometry) VALUES (
sde.st_point (3, 8, 23, 7, 4326)
);
SELECT id, sde.st_m (geometry)
AS M_COORD
FROM m_test;
id m_coord
1 5
2 4
3 7
SQLite
In the first example, the table, m_test, is created and three points inserted to it. All three contain measure values. A SELECT statement is run with the ST_M function to return the measure value for each point.
CREATE TABLE m_test (
id integer primary key autoincrement not null
);
SELECT AddGeometryColumn (
NULL,
'm_test',
'geometry',
4326,
'pointzm',
'xyzm',
'null'
);
INSERT INTO m_test (geometry) VALUES (
st_point (2, 3, 32, 5, 4326)
);
INSERT INTO m_test (geometry) VALUES (
st_point (4, 5, 20, 4, 4326)
);
INSERT INTO m_test (geometry) VALUES (
st_point (3, 8, 23, 7, 4326)
);
SELECT id, st_m (geometry)
AS M_COORD
FROM m_test;
id m_coord
1 5.0
2 4.0
3 7.0
In this second example, the measure value is updated for record 3 in the m_test table.
SELECT st_m (geometry, 7.5)
FROM m_test
WHERE id = 3;