Populate A New Field Based On The First Portion Of An Existing Field

I am working on a database project and one of the tasks is to populate a newly created field 'institution' with the first portion of the field course_id which is HarvardX/CB22x/201

Solution 1:

You can use substring_index():

update mytable
set institution = substring_index(course_id, '/', 1)

If you want to also extract the middlde part and end part, then:

update mytable
set 
    institution = substring_index(course_id, '/', 1),
    other_col   = substring_index(substring(course_id, locate('/', course_id) +1), '/', 1),
    more_col    = substring_index(course_id, '/', -1)