t, MySQL - rextester

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DROP TABLE IF EXISTS locations;
DROP TABLE IF EXISTS polyThing;

CREATE TABLE `locations` (
  `LocationID` int(11) NOT NULL,
  `Location` varchar(200) NOT NULL,
  `Longitude` varchar(200) NOT NULL,
  `Latitude` varchar(200) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1 ROW_FORMAT=COMPACT;

INSERT INTO `locations` (`LocationID`, `Location`, `Longitude`, `Latitude`) VALUES
(1, 'In the polygon', '-114.007191', '46.853019'),
(2, 'In the polygon', '-114.003798', '46.851045'),
(3, 'Not in', '-114.016934', '46.866098');

CREATE TABLE polyThing
    (
        `ID` int auto_increment primary key,
        `boundary` polygon not null,
        `testarea` varchar(200) NOT NULL
    );

INSERT INTO polyThing (boundary, testarea)
VALUES(
    PolygonFromText(
        'POLYGON(( 
                -114.018522 46.855932 ,
                -113.997591 46.856030 ,
                -113.997447 46.848626 ,
                -114.018161 46.848824 ,
                -114.018522 46.855932 ))'
         ), 'Test Area 1'
     );

SELECT l.*,  ST_CONTAINS(p.boundary, POINT(l.Longitude, l.Latitude))
 FROM locations l
 CROSS JOIN polyThing p;
 
SELECT l.*
FROM locations l
JOIN polyThing p
  ON ST_CONTAINS(p.boundary, POINT(l.Longitude, l.Latitude))
 AND p.testarea = 'Test Area 1';


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