MYSQL根据CASE语句选择列

Question

I have a MYSQL query that selects data from my database and repeats one column upto 5 times based on a comma separated value in the table, sometimes there is only one or 2 sometimes all five.

If there is only 2 I end up with the 2nd set of results repeated another 3 times. I am wanting to amend the query to count the number of substrings in the string and only repeat the code that number of times.

The code would be something similar to this -

Select name, age, location, options
CASE WHEN options = 5
THEN option1, option2, option3, option4, option5
ELSE WHEN options = 4
THEN option1, option2, option3, option4
ELSE END FROM test_table

Answer 1

If you are trying to pull options into a column using substring_index() , then:

select t.*,
       substring_index(options, 1, ',') as option_1,
       (case when options like '%,%'
             then substring_index(substring_index(options, 2, ','), ',', -1)
        end) as option_2,
       (case when options like '%,%,%'
             then substring_index(substring_index(options, 3, ','), ',', -1)
        end) as option_3,
       . . . 
from test_table t;