Questions And Answers for PowerBuilder Interviews

Question

Explain the DataWindow validation.

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Answer

PowerBuilder checks whether the data is changed or not by comparing the edit control value with primary buffer. It checks for the data type correctness, if the data is changed. Wrong data type will trigger ItemError event. When the data passes the data type checking, it executes the validation rule. Invalid data will trigger ItemError event. Correct data will trigger ItemChanged event. If the ItemChanged event returns zero, it will trigger ItemFocusChanged event, otherwise ItemError will be triggered. Depending on the ItemError event's return value, either the cursor remains in the same column or will go to the next higher tab sequence's field (In this case, ItemFocusChanged event will be triggered).

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