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Faster MySQL Join DISTINCT Records

After considering related issues, none of them seem to turn to mine, so it says:

I have two tables containing course information. One table [course] currently stores almost 25 thousand records with fields such as CourseName, CourseCode, Term, Instructor, etc. The second table [courseCatalog] contains only CourseCode and CourseName.

My application allows users to pull up instructors and approve courses from the list that they are allowed to teach.

I built a search using an automatic suggestion (jQuery Ajax Object -> PHP file -> MySQL and vice versa) to find courses. When they are returned, the user can click the course to mark (Another Ajax call for PHP and MySQL) as an approved course for the instructor.

The problem is that there are several courses in the large table that are not in the smaller table, and vice versa (fixing this problem is a much more complicated problem based on where the data actually comes from, I get distracted)

If I join tables in any particular field, some courses are not taken into account. LEFT JOIN still seems to be giving the same problem, because I have to join the field.

If I just call both tables:

SELECT DISTINCT course.CourseCode, course.CourseName
FROM course, courseCatalog

FOREVER, , .

DISTINCT, "" "courseCatalog"... :)

? - ?

+3
1

, , , , ( , ), DISTINCT, course. ( , SELECT DISTINCT CourseCode, CourseName FROM course)

CourseCodes CourseNames , UNION.

SELECT CourseCode, CourseName
FROM course
UNION /*Will ensure DISTINCTness*/
SELECT CourseCode, CourseName
FROM courseCatalog
ORDER BY CourseCode, CourseName
+2

Source: https://habr.com/ru/post/1762669/

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