Sunday, October 18, 2009

Cascading List Views in Forms

Razzak showed a technique using a series of Variable List View controls in a single variable form. Each did a lookup, and the second and third each had a variable in its WHERE clause that refered to the variable set by a click in the earlier list view.


It created a drill-down interface, with a performance advantage over using DB Grids or other DB controls: None of the three tables involved was ever locked by a user (unless and until a double-click brought up an edit form).

That technique can be used in 7.6 or 8.0, also. But Razzak went on to show many new features of eXtreme 9.0. For example, more EEPs are possible, and it is easier to get to the EEP you want to edit. You can make the form "scroll up" like a window shade to gain screen real estate, or to hide private information when somebody walks up behind you.

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