Error 1045 is returned when a user is denied permission to connect to the MySQL server.

Sample

[localhost]$ mysql
ERROR 1045 (28000): Access denied for user ‘root’@'localhost’ (using password: NO)

Resolution

• If the message ends with ‘(using password: NO)’, no password was specified while connecting. Add -p to the call to the mysql client:
  

  mysql -p

• If the username in the error message is not the one you need to use to connect to MySQL, specify the desired username with the -u flag:
  

  mysql -u mike -p

  When -u is omitted, the mysql client uses the logged-in username on the OS (root in the example above).

• Authentication is based on a combination of user and the host being connected from (’root’ connecting from ‘localhost’ in the example above). Check that the connecting host listed is the one you have permission to connect from.
• If you are connecting from the correct host using the correct username, it means that you are providing the wrong password or the user does not exist. See the Adding Users link in the following section.

Further Reference

Causes of Access Denied Errors (MySQL Reference Manual)

Connecting to the MySQL Server (MySQL Reference Manual)

Adding New User Accounts to MySQL (MySQL Reference Manual)

Error 1033 generally points to corruption of the .frm file for the table being queried. This can be caused by InnoDB reconfiguration, form file corruption, and permissions issued.

Sample

SELECT COUNT(*) FROM auth;
ERROR 1033 (HY000): Incorrect information in file: './auth/auth.frm

Resolution

• Check that the permissions on /tmp/ allow for reading and writing by the mysql user.
• Stop MySQL, delete the ib_logfile0 and ib_logfile1 files from your MySQL datadir and start MySQL.
• Restore from a backup.

Further Reference

Explanation of Error 1033 in relation to InnoDB

Explanation of Error 1033 and /tmp/

Error 17 indicates that that either the MySQL server encountered an issue while trying to delete the directory containing the database to be dropped, or tried to create a temporary file that already existed during an ALTER TABLE statement.

Sample

mysql> DROP DATABASE foo;
Error dropping database (can’t rmdir ‘./foo/’, errno: 17)

mysql> ALTER TABLE foo …
Error on rename of ‘./bar/foo.frm’ to ‘./bar/B-foo.frm’ (Errcode: 17)

Resolution

• Check that the user the MySQL server is running under has permission to delete the directory.
• Check that there are no files in the directory that are not created by the MySQL server.
• Browse to the MySQL data directory and delete all files whose names start with A- or B-.
• Shut down MySQL, manually delete the directory listed.
• Use the latest version of MySQL.
• Use the mysqld-nt binaries when using Windows NT-based hosts.

Further Reference

Bug report related to Error 17 on bugs.mysql.com

perror - Explain Error Codes (MySQL Reference Manual)

Problems with ALTER TABLE (MySQL Reference Manual) 

Error 2003 indicates that the mysql client was unable to establish a connection with the MySQL server you specified.

Sample

C:\Documents and Settings\Administrator>mysql -u root -h 127.0.0.1 -p
Enter password: *****
ERROR 2003 (HY000): Can’t connect to MySQL server on ‘127.0.0.1′ (10061)

Resolution

• Did you specify the correct hostname or IP address for the MySQL server? If you do not specify one, the local machine is used as a default.
• Is the MySQL server running? Check the process list on the server machine.
• Is there a firewall blocking port 3306 at some point between the client and server? (If you are trying to reach a server provided by a hosting company this is likely).
• Is the MySQL server configured to listen on port 3306? If not, you need to specify the right port number with the -P option.

Further Reference

Client Error Codes and Messages (MySQL Reference Manual)

Experts-Exchange Question on Error 2003

Accessing MySQL Through a Firewall With SSH Port Forwarding