Retrieve data from SQL

Hello,


hi I would like to ask your opinions on how the current log in user can view the data that he/her entered. For example, I am building expenses tracking system. Users can insert all the expenses spent by them by select the month ( drop down menu) which I already made and the expenses by insert them in each text boxes. After they've confirmed the items, the system will submit all the data in the database (sql).

How can I retrieve only the row that related to the current username to be shown in gridview of something else> I am working with ASP.NET in C# language.