>after i use a logical field for my table, i still dunno know how to put my checkbox in the grid. what do i do now? as i know, i cannot add the checkbox into my grid.

It's easy. You're using vfp base classes, I assume? Just right-click grid to edit, click on column, select checkbox from Form Controls, and click on column. Checkbox will appear. To remove default textbox, select textbox in PEM sheet, click on column again, and hit delete button.

Also, make sure Sparse is .F. for checkbox column, and caption is blank.

You can get a little more elaborate and center the checkbox by placing it in a container, but just try to get the basics working first...