Questions And Answers for PowerBuilder Interviews

Question

Explain different ways of generating a serial number for a column in a table. Explain ways in PowerBuilder and in the database. Which method you recommend?

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Answer

This has to be controlled from the database, not from the PowerBuilder. This is because, a unique serial number generated by a POWERBUILDER client may not be unique for other user or when it is put in the database. If the database supports auto incrementing (Different database vendors implement it in different ways, for ex: sybase implements using Identity column property, Watcom calls AutoIncrement, Oracle selects from a special table), then there is no problem. Otherwise, you can use a single row single column table to generate serial no. The method you choose might depend on the performance issues and number of expected inserts and other factors.

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