mysql - Create a virtual column to verify if data exists on anothers -

mt_user:

usr_id               usr_login          usr_passwd   1                   user1               user1   2                   user2               user2   3                   user3               user3   4                   user4               user4 

mt_settings:

sttgs_id                        sttgs_description    1                                 setting 1    2                                 setting 2    3                                 setting 3    4                                 setting 4    5                                 setting 5 

mt_user_settings:

uss_id               usr_id                   sttgs_id   1                    1                         1   2                    1                         2   3                    2                         5   4                    3                         2   5                    3                         3   6                    3                         5   7                    4                         4 

what need show data this:

where usr_id='2' :

sttgs_id                   sttgs_description                 has it? (virtual_column)    1                          setting 1                              0    2                          setting 2                              0    3                          setting 3                              0    4                          setting 4                              0    5                          setting 5                              1 

where usr_id='3' :

sttgs_id                   sttgs_description                 has it? (virtual_column)    1                          setting 1                              0    2                          setting 2                              1    3                          setting 3                              1    4                          setting 4                              0    5                          setting 5                              1 

how correctly?

select s.sttgs_id, s.sttgs_description, if(st.uss_id,1,0) `has it` mt_user u join mt_settings s left join mt_user_settings on us.usr_id = u.usr_id , us.sttgs_id = s.sttgs_id u.usr_id = 2 

you can without users table

select s.sttgs_id, s.sttgs_description, if(st.uss_id,1,0) `has it`  mt_settings s left join mt_user_settings on us.usr_id = 2 , us.sttgs_id = s.sttgs_id