DBISAM UPDATE:

UPDATE 
  TestResult
SET 
  SequenceNo = Test.SequenceNo
FROM
  TestResult INNER JOIN Test
     ON TestResult.TestID = Test.ID
WHERE
  TestResult.SequenceNo <> Test.SequenceNo;

ElevateDB UPDATE:

UPDATE
  TestResults
SET
  SequenceNo = (SELECT SequenceNo FROM Test
                             WHERE TestResults.TestID = Test.ID)
WHERE EXISTS
  (SELECT * FROM Test
     WHERE
        TestResults.TestID = Test.ID AND
        TestResults.SequenceNo <> Test.SequenceNo);

Tables:

CREATE TABLE "Test"
(
"ID" INTEGER GENERATED BY DEFAULT AS IDENTITY (START WITH 146, INCREMENT BY 1) NOT NULL,
"Name" VARCHAR(24) COLLATE "ANSI_CI" NOT NULL,
"SequenceNo" INTEGER NOT NULL,
"Abbreviation" VARCHAR(12) COLLATE "ANSI" NOT NULL,
. . . . .
)
  
CREATE TABLE "TestResult"
(
"ID" INTEGER GENERATED BY DEFAULT AS IDENTITY (START WITH 1353957, INCREMENT BY 1) NOT NULL,
"ClientEpisodeID" INTEGER NOT NULL,
"TestID" INTEGER NOT NULL,
"Result" FLOAT,
"SequenceNo" INTEGER DEFAULT 0  NOT NULL,
. . . . . 
)