Flex is only one piece of the puzzle in this case. You're going to need a mechanism on the server-side to mitigate communication between Flex and SQL, like Java, PHP, .NET, etc. Now you can modify one of the examples you've seen to do an INSERT or UPDATE SQL statement instead of SELECT and accomplish the goal that way. Look at some of the documentation regarding "Data Services" in Flex. Bottom line, you're going to need more than just a Flex swf to send and retrieve data from your server.