Assign random student_id to test users

Assign random student_id (9xxxxxx) to test users in a particular class with user_id starting with xx
reference: Update a SQL Server Column with Random Numbers within a Range

UPDATE u
SET student_id = ABS(CHECKSUM(NEWID())) % 1000000 + 9000000
FROM users u
INNER JOIN course_users cu ON u.pk1 = cu.users_pk1
INNER JOIN course_main cm ON cu.crsmain_pk1 = cm.pk1
WHERE u.user_id LIKE 'xx%' AND cm.course_id = 'INT-Testcourse'