>>>Is it possible to set a different tool tip text for each element of combobox according selected option by the user?
>>What do you mean?
>>Each Item has its own Tooltip, or when the user selects an item then the Tooltip of the combo changes.
>>If you want the second:
>>In InterActiveChange Event of the combo put:
>>

>>this.ToolTipText = [whatever you want]
>>

>
>In the second case. How to set tooltiptext based on column table name. I have tried these: tablename.field, &tablename.field. The content of tablename.field is not showed
>
>In the first case. Is it possible to do?

Try
evaluate(tablename.field)