Excel has the Microsoft Query window that can be accessed via the External Data toolbar. It can be set to allow the user to edit data under “Records”->“Allow Editing”. I don’t think that there’s an easy way to “tie” data between Excel and an SQL database bi-directionally (MS SQL Server or MySQL). You can use VBA scripting within Excel to accomplish this functionality, but this probably isn’t what you had in mind.
I think what may be relevant for you is to use MS Access as a Frontend to MySQL. This is done via Linked Tables, which is described here.