When you are using a PHP superglobal array such as $_SESSION or $_GET, and you want to access a value in that array, when would you put single quotes around the key value in the square brackets, and...

When you are using a PHP superglobal array such as $_SESSION or $_GET, and you want to access a value in that array, when would you put single quotes around the key value in the square brackets, and when would you not do this? 10. Suppose you are logged in to MySQL and you are at the command-line interface and connected to the appropriate database. If you are monitoring some “behind-the-scenes” database activity using a script called check_it.sql and that script is in your current directory, what command would you give to execute the script?