现在我有了这个MySQL存储过程，但是我如何检查该行是否已经存在呢？

CREATE DEFINER=`edmetrics`@`%` PROCEDURE `CreateTestJob`(JobLink varchar(300), StartTime datetime, Endtime datetime, Owner_info varchar(45), Engine_info varchar(100), TestSuiteId INT, TestSuiteCollectionId INT, Finished varchar(45), JenkinsBuild INT(100), JenkinsJobName varchar(100))
BEGIN

    IF TestSuiteId = '' THEN
    SET TestSuiteId = null;
    END IF;

    IF TestSuiteCollectionId = '' THEN
    SET TestSuiteCollectionId = null;
    END IF;

    IF TestSuiteCollectionId != '' THEN
    SET TestSuiteId = null;
    END IF;

    INSERT INTO TestJob (`id`,`JobLink`,`StartTime`,`Endtime`,`Owner`,`Engine`,`TestSuiteId`,`TestSuiteCollectionId`,`Finished`,`JenkinsBuild`,`JenkinsJobName`) 
    VALUES (NULL, JobLink, StartTime, Endtime, Owner_info, Engine_info, TestSuiteId, TestSuiteCollectionId, Finished, JenkinsBuild, JenkinsJobName);
    SELECT LAST_INSERT_ID() AS LastInsertId;

END

因此，按照建议，我应该使用if exists，但一个变量为空，然后将其设置为null，如果不是，那么就有一个变量。但这会使它有点困难，因为这行不通：

BEGIN
    declare return_id int;

    IF TestSuiteId = '' THEN
    SET TestSuiteId = null;
    END IF;

    IF TestSuiteCollectionId = '' THEN
    SET TestSuiteCollectionId = null;
    END IF;

    IF TestSuiteCollectionId != '' THEN
    SET TestSuiteId = null;
    END IF;

    IF (EXISTS(SELECT 
        `JobLink`,
        `StartTime`,
        `Endtime`,
        `Owner`,
        `Engine`,
        `TestSuiteId`,
        `TestSuiteCollectionId`,
        `Finished`,
        `JenkinsBuild`,
        `JenkinsJobName`
        FROM
            testreportingdebug.testjob
        WHERE
            `JobLink` = JobLink
                AND `StartTime` = StartTime
                AND `Endtime` = Endtime
                AND `Owner` = Owner_info
                AND `Engine` = Engine_info
                AND `TestSuiteId` = TestSuiteId
                AND `TestSuiteCollectionId` = TestSuiteCollectionId
                AND `Finished` = Finished
                AND `JenkinsBuild` = JenkinsBuild
                AND `JenkinsJobName` = JenkinsJobName LIMIT 1))
    THEN
        SET return_id = -1;
    ELSE 
        INSERT INTO TestJob (`id`,`JobLink`,`StartTime`,`Endtime`,`Owner`,`Engine`,`TestSuiteId`,`TestSuiteCollectionId`,`Finished`,`JenkinsBuild`,`JenkinsJobName`) 
        VALUES (NULL, JobLink, StartTime, Endtime, Owner_info, Engine_info, TestSuiteId, TestSuiteCollectionId, Finished, JenkinsBuild, JenkinsJobName);
        SET return_id = LAST_INSERT_ID();
    END IF;

    SELECT return_id AS LastInsertId;

END

这将只工作，如果所有变量都设置，如果一个或多个是null那么它不工作。因为你不能说varaible = null，而只能说variable is null和其他方式。我该如何解决这个问题？