My mysql database crashed, how to recover
I included this line in my.ini according to the doc http://dev.mysql.com/doc/refman/5.6/en/forcing-innodb-recovery.html: innodb_force_recovery = 1
The server started
I created a dump of each database using mysqldump
According to http://blackbird.si/mysql-corrupted-innodb-tables-recovery-step-by-step-guide/, I ran a database check with mysqlcheck --all-databases and found the offending table.
I tried to delete that table, but it was linked with primary keys (mysql -u ... -p... -e "drop database ..."). I deleted the depending tables, but with no luck, mysqld still refused to start with innodb_force_recovery = 0


I decided to start off from scratch to be sure to get a clean database back.


I deleted everything in the data directory (keeping a backup copy).
I initialized the innodb datafiles using mysqld --initialize, according to https://dev.mysql.com/doc/refman/5.7/en/data-directory-initialization-mysqld.html
I copied the two system database files from the backup (directories mysql and performance_schema)
Now the server started again with these warnings in the log:


  [Warning] InnoDB: Cannot open table mysql/slave_master_info from the internal data dictionary of InnoDB though the .frm file for the table exists. See http://dev.mysql.com/doc/refman/5.6/en/innodb-troubleshooting.html for how you can resolve the problem.
  [Warning] Info table is not ready to be used. Table 'mysql.slave_master_info' cannot be opened.


the same for mysql/slave_relay_log_info and mysql/slave_worker_info
According to https://dev.mysql.com/doc/refman/5.6/en/innodb-troubleshooting-datadict.html, I deleted the three files mysql/slave_master_info.frm, mysql/slave_relay_log_info.frm and mysql/slave_worker_info.frm
I imported the three tables from the dump of the mysql database.


At this point I got a working mysql server with a clean database. The olny thing that remained was to import the dumps that I made previously, using mysql -u root -p... mydb &lt; backup-mysql\mydb.sql

And thank God, after one hour of interruption, everything was working again.