Maintenance View customize

Hi everybody,

     I encountered one problem that I don`t know how to solve , that is :

     I use maintenance view to maintain data , but the data in this table can have up to 1 line, so in the maintenance view ,when click "new entries" or "copy", it make sense to check if the DB is have one line already, and pop up the messages. But I don`t know how to do this .

     And another question , I want to display the maintenance view`s column according to the configuration of from other table ,for example ,read data from other table , in one condition, all columns of table is displayed for maintenance , in other condition, only some columns are displayed for maintenance ,some columns are hidden, how to do this?

     Thanks very much.

Best regards,

Xu Chris