Updating the database table

Hi,

I'm a fresher n facin a problem while workin with table control...I have created a screen in which i'm passing the sales order and its corresponding invoice number,as a result the data related to that particular invoice number is getting fetched in a table control..Three fields are getting fetched namely text,value and text1.These fields are getting fetched by a ztable that i have created.Now i want to edit the contents being fetched and for that particular invoice number the ztable should be gettin updated for whatever changes i have done to the fetched fields.. text is a primary key in my ztable..

Please try to guide me through this problem..