Question

I’m writing a SQL statement to select a user on a table if that user does not exist on another table, then I want to pull in all their data from another table then I’ll be outputting all that in Coldfusion.

How do I do this? I have tried, my atempt is below:

pro_profile == All employees
mod_userStatus == All Professional Staff members
I am doing the not exists to remove professional stuff to just get our student staff.
mod_StudentCertifications is a listing of the certifications they (students) hold.

If we do an AND statement between the where statements it returns no users, or only users that meet both conditions, if we do an OR it will return users with only 1 condition. I need it first Match the not exists then proceed to the exists statement.

Is that do able?

Here’s my Statement:

SELECT profileID, firstName, lastName
FROM pro_Profile
WHERE not exists (
         SELECT profileID
         FROM mod_userStatus
         WHERE mod_userStatus.profileID = pro_Profile.profileID
        )             
        OR            
        exists (
          SELECT          
            cprAdultExp,
            cprInfantChildExp,
            cprFPRExp,
            aedExp,
            firstAidExp,
            emtExp,
            waterSafetyInstructionExp,
            bloodPathogensExp,
            oxygenAdminExp,
            lifegaurdingExp,
            wildernessResponderExp,
            notes
         FROM mod_StudentCertifications
         WHERE mod_StudentCertifications.profileID = pro_Profile.profileID       

        );

Answer 1

For a “complete” pull:

SELECT p.profileID, p.firstName, p.lastName, sc.cprAdultExp, sc.....
FROM pro_Profile AS p
   LEFT OUTER JOIN mod_StudentCertifications AS sc ON sc.profileID = p.profileID
WHERE p.profileID NOT IN
    (
       SELECT profileID
       FROM mod_userStatus
    )
;

For a single “profile” pull:

SELECT p.profileID, p.firstName, p.lastName, sc.cprAdultExp, sc.....
FROM pro_Profile AS p
   LEFT OUTER JOIN mod_StudentCertifications AS sc ON sc.profileID = p.profileID
WHERE p.profileID = ?
    AND p.profileID NOT IN      
    (
       SELECT profileID
       FROM mod_userStatus
       WHERE profileID = ?
    )
;

EDIT: Looked at the execution plan of using a LEFT OUTER JOIN for mod_userStatus and checking it’s primary key for null VS a NOT IN statement in a similar setup. The NOT IN statement is indeed less costly.

The LEFT OUTER JOIN performs a filter & hash match (Cost: 2.984):

While the NOT IN performs a merge join (Cost: 1.508):