Hello, I would like to combine the observations, for each study_id in one row

example
study_id DoSam_d0_d0 DoSam_d30 tcv_bc_d0 tcv_ser_d0 tcv_ser_d30 tcv_ss_d30
1001 31/07/2019 . TCV042 TCV042 . .
1001 . 29/08/2019 . . TCV099 TCV099
1003 01/08/2019 . TCV044 TCV044 . .
1003 . 29/08/2019 . . TCV103 TCV103
1004 . 30/08/2019 . . TCV106 TCV106
1004 02/08/2019 . TCV047 TCV047 . .
1005 . 30/08/2019 . . TCV107 TCV107
1005 02/08/2019 . TCV048 TCV048 . .
1006 . 30/08/2019 . . TCV108 TCV108
1006 05/08/2019 . TCV049 TCV049 . .
to get this:
study_id DoSam_d0_d0 DoSam_d30 tcv_bc_d0 tcv_ser_d0 tcv_ser_d30 tcv_ss_d30
1001 31/07/2019 29/08/2019 TCV042 TCV042 TCV099 TCV099
1003 01/08/2019 29/08/2019 TCV044 TCV044 TCV103 TCV103
1004 02/08/2019 30/08/2019 TCV047 TCV047 TCV106 TCV106
1005 02/08/2019 30/08/2019 TCV048 TCV048 TCV107 TCV107
1006 05/08/2019 30/08/2019 TCV049 TCV049 TCV108 TCV108
please could you advise on which command to use, thanks
Maria