I tend to use MySQL from the interactive command line shell quite a bit (SSH to your db server and type the command mysql to start). I noticed today that there is a pretty extensive built in help system in this command.

You can access it by typing help COMMAND, so for instance if you type help ALTER TABLE you get a quick reference for constructing an ALTER TABLE statement.

If you can't remember what command you want to use, then typing help contents is your friend. It will output:

For more information, type 'help item', where item is 
one of the following categories:
   Administration
   Column Types
   Data Definition
   Data Manipulation
   Functions
   Geographic features
   Transactions

So if your looking for that command that outputs all the columns in a table, but don't know what it's called, you might now try help administration and it will tell you:

For more information, type 'help item', where item is 
one of the following categories:
   ANALYZE
   BACKUP TABLE
   CHECK
   CHECKSUM
   CONSTRAINT
   CREATE USER
   DESCRIBE
   FLUSH QUERY CACHE
   GRANT TYPES
   MERGE
   RENAME USER
   REPAIR
   RESET SLAVE
   RESTORE
   SET GLOBAL SQL_SLAVE_SKIP_COUNTER
   SET PASSWORD
   SHOW SLAVE STATUS
   START SLAVE
   STOP SLAVE

Yes ofcourse the command to show the columns in a table is called DESCRIBE, and you can get the help for it by typing help DESCRIBE (you pretty much just run DESCRIBE tableName)