TIP: Unlike Linux commands, MySQL commands need a semicolon (;) on the end to execute.
If ever you mistakenly end a command string with no semicolon...
CREATE DATABASE us_presidents
...then press ENTER...
...there is no way to "fix" that command.
To continue, just add a semicolon to the new line you are on:
CREATE DATBASE us_presidents
;
If the command is valid, it will execute.
If there was an error in the command string and it's invalid, adding a semicolon here will execute it and MySQL will give an error. Then you can continue from there.