mysqlif-statementselect-query

Using an IF Statement in a MySQL SELECT query

I am trying to use an IF statement in a MySQL select query.

I am getting an error after the AND statement where the first IF.

SELECT J.JOB_ID,E.COMPANY_NAME,J.JOB_DESC,JT.JOBTYPE_NAME,J.COMPENSATION,ST.STATE_NAME,MC.METRO_CITY_NAME,I.INDUSTRY_NAME,
 J.JOB_CONTACT_PERSON,J.DT_INSRT,J.JOB_TITLE,J.JOB_EXP_DATE,J.SKILLS
 FROM JOBS J 
 JOIN EMPLOYER E ON J.COMPANY_ID=E.COMPANY_ID 
 JOIN LOOKUP_JOBTYPE JT ON J.JOB_TYPE=JT.JOBTYPE_ID
 JOIN LOOKUP_STATE ST ON J.STATE_ID=ST.STATE_ID
 JOIN JOBS_LOCATION JL ON J.JOB_ID=JL.JOB_ID
 JOIN LOOKUP_METRO_CITY MC ON JL.METRO_CITY_ID=MC.METRO_CITY_ID
 JOIN LOOKUP_INDUSTRY I ON J.INDUSTRY_ID=I.INDUSTRY_ID 
 JOIN JOBS_QUALIFICATION JQ ON J.JOB_ID=JQ.JOB_ID 
 JOIN LOOKUP_DEGREE_QUALIFICATION LDQ ON LDQ.QUALIFICATION_ID = JQ.QUALIFICATION_ID
 WHERE  J.ACTIVE='Y' AND J.DT_INSRT > COALESCE(pEmailSntDt,DATE_SUB(SYSDATE(),INTERVAL 4 DAY))  
AND
IF(JQ.COURSE_ID=0) 
THEN
IF(JQ.DEGREE_ID=0)
THEN J.SKILLS LIKE CONCAT('%', pSkills,'%')
ELSE
JQ.DEGREE_ID=pDegreeId OR J.SKILLS LIKE CONCAT('%', pSkills,'%')
END IF
ELSE
JQ.COURSE_ID=pCourseId OR IF(JQ.DEGREE_ID=0)
                      THEN
                      J.SKILLS LIKE CONCAT('%', pSkills,'%')
                      ELSE
                      JQ.DEGREE_ID=pDegreeId OR J.SKILLS LIKE CONCAT('%', pSkills,'%')
                      END IF
END IF                           
GROUP BY J.JOB_ID ORDER BY J.DT_INSRT DESC;

Why doesn't this work and what is the proper way to do an IF statement in a MySQL query?

Solution

  • The IF/THEN/ELSE construct you are using is only valid in stored procedures and functions. Your query will need to be restructured because you can't use the IF() function to control the flow of the WHERE clause like this.

    The IF() function that can be used in queries is primarily meant to be used in the SELECT portion of the query for selecting different data based on certain conditions, not so much to be used in the WHERE portion of the query:

    SELECT IF(JQ.COURSE_ID=0, 'Some Result If True', 'Some Result If False'), OTHER_COLUMNS
FROM ...
WHERE ...