Hour 19

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Quiz Answers

1:	CommandBuilder will generate UPDATE and DELETE statements following which concurrency model? Pessimistic concurrency model Optimistic concurrency model Data update concurrency model
A1:	b. The optimistic concurrency model, which means that other users can update data that has been selected by your application and your application must check for this before committing your updates.
2:	True or false: Automatically generated commands will be created for all SelectCommands coded in Visual Basic or C#.
A2:	False. You must explicitly activate this capability by using the CommandBuilder object.
3:	What must be done following the change of a SELECT statement when using CommandBuilder to automatically generate code? Reassign SELECT variables Refresh metadata Close connection Open connection
A3:	b. Refresh metadata. This is done using the .Refreshschema() method. You would then clear out ( .Remove ) the DataSet and fill it again for further processing.
4:	True or false: The following SELECT statement is valid for using with CommandBuilder : SELECT a.*, b.* FROM Customers a, Orders b WHERE a.CustomerID = b.CustomerID
A4:	False. The SelectCommand to be used with CommandBuilder must not span multiple tables.
5:	The SelectCommand that will be used for the CommandBuilder must: Include a SELECT Distinct clause Contain all columns in the table Return at least one primary key or unique column Contain a WHERE clause with at least one filter
A5:	c. Return at least one primary key or unique column. The UPDATE and DELETE statements must be able to locate the exact data row for update/delete to ensure integrity.

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