The prompt that shows when you are using the MySQL client tells you a lot about what's going on.
The normal prompt looks like this:
mysql>
This means it is waiting for you to enter an SQL query.
If you are in the middle of entering an SQL query, it will be waiting for a semi-colon to terminate the query, and will look like this:
->
If you have opened a set of quotes but not closed them, you will see one of these prompts:
'> ">