MySQL 1170: Cannot open database.

What is MySQL 1170: Cannot open database.

Check if the MySQL service is running:

- On Linux, run: `sudo systemctl status mysql` - On Windows, open Services and look for MySQL service.

Verify MySQL server is reachable:

- Run: `mysql -h [hostname] -u [username] -p`

Check database existence:

- Connect to MySQL: `mysql -u [username] -p` - List databases: `SHOW DATABASES;` - Ensure the targeted database is listed.

Examine user privileges:

- After connecting to MySQL: `SHOW GRANTS FOR 'youruser'@'yourhost';`

Review error logs for specific error messages:

- Default location on Linux: `/var/log/mysql/error.log` - On Windows, located in MySQL installation directory, `data` folder.

Check for disk space:

- On Linux: `df -h` - On Windows: Open This PC and check the disk where MySQL is installed.

Assess MySQL server status and variables:

- Connect to MySQL and run: `SHOW STATUS LIKE 'uptime';` to check if the server is running. - Check open connections: `SHOW STATUS LIKE 'Threads_connected';`

Repair database in case of corruption (if the database is marked as crashed or corrupted):

- Connect to MySQL and run: `REPAIR TABLE tablename;` for the specific table(s) reported in errors, or - Use myisamchk for MyISAM tables if the server is stopped: `myisamchk --recover /path/to/table.MYI`

Increase connection limits if too many connections:

- Check max connections: `SHOW VARIABLES LIKE 'max_connections';` - Temporarily increase: `SET GLOBAL max_connections = [higher number];`

Restart MySQL Service:

- On Linux: `sudo systemctl restart mysql` - On Windows: Restart the MySQL service from Services.Perform these actions in sequence, checking after each step if the error persists before proceeding to the next.