Thanks for your help @dec0de,
I just found a solution, too and it worked out quite perfectly for my case, using mysql, Ubuntu 18 and Nextcloud 18.04.
Just follow those instructions:
-
Go to mysql and enrol as nextcloud
sudo mysql -u root -p
use nextcloud -
type in following lines
CREATE TABLEoc_talk_participants_tempLIKEoc_talk_participants;
CREATE UNIQUE INDEXtp_identONoc_talk_participants_temp(room_id,user_id,session_id);
INSERT IGNORE INTOoc_talk_participants_tempSELECT * FROMoc_talk_participants;
DROP TABLEoc_talk_participants;
ALTER TABLEoc_talk_participants_tempRENAME TOoc_talk_participants; - exit mysql