I am trying to compare two tables and only return from the first table records that do not have a match for a specific attribute in the 2nd
attributeData table. We store lots of attributes in one table.
This is to return courses that have not had a specific email sent and record in that attributeData Table.
It works fine on the server via
phpMyAdmin but running it results in the
MAX_JOIN_SIZE error even with big select on.
FROM studentCourse, attributeData
WHERE NOT EXISTS
SELECT attributeData.entityID FROM attributeData
WHERE attributeData.entityID = studentCourse.studentCourseId
AND (studentCourse.startDate >= '2017-12-15')
AND attributeData.attributeID = 244
AND (studentCourse.sclLastLessonDate = '0000-00-00')
Any help would be greatly appreciated as would help with the issue we are having using the school system.
Has to be a way to make the query compare and since the returned data is not large (say 30 rows)