mysql - How to concatenate a list with conditional entries to one string with SQL -

i need create csv file includes field, different elements should listed, based on condition each entry.

in example have table

id    col1    col2    col3 1     false   false   true 2     true    true    true 3     true    false   true 

the csv should this:

id,params "1","col3" "2","col1,col2,col3" "3","col1,col3" 

i thought of this:

select      id,     concat(         if(`col1`, 'col1,',''),          if(`col2`, 'col2,',''),          if(`col3`, 'col3','')     ) `params` `table` 

but problem is, work if last column (col3) true, otherwise have trailing comma @ end.

is possible in mysql sql dialect?

use null instead of empty string in if conditions , use concat_ws concatenate values.

select id, concat_ws(',',c1,c2,c3) params (select        id,       if(`col1`, 'col1',null) c1,        if(`col2`, 'col2',null) c2,        if(`col3`, 'col3',null) c3       t) x 

or

select id, concat_ws(',',if(col1,'col1',null),if(col2,'col2',null),if(col3,'col3',null)) params t