FAQs about Rowset/View/Index

1. I find that it is difficult to handle a statement like "Select * from Orders where OrderID in (?, ?, ?, .....)" with ATL consumer templates. Can OleDBPro handle this statement easily?
           Yes! All the OleDBPro classes and templates are 100% generic and dynamic to handle any one of statements with no requirement of schema data at the design time at all, no matter how complicate the statement is. For how to deal with the above statement using OleDBPro, see the provided examples Scroll and MultiRecords. 

2. How about TCHAR in OleDBPro module? Can I use TCHAR data type with CRBase based classes and templates?
           Yes! We can easily use TCHAR data type with CRBase based classes and templates by calling CRBase::SetDataType. If the size of TCHAR is 1, the data type should be set to DBTYPE_STR for a string. Otherwise, the data type should be DBTYPE_WSTR.

3. I am able to use MS Access providers with some ISAM drivers to read records with no problems, but I failed to update records. Why?
           You can use jet providers to read ISAM database files such as dBase, Paradox, Text, HTML, and so on. However, you may have problems in updating, adding and deleting records. To update ISAM database files, you need to contact Borland for Borland database engine. Microsoft also has updateable ISAM drivers for dBase and Paradox files too.

4. I know most of providers don't support OLEDB TView object and can't open a COView directly. With the help of MS Client Cursor Engine, I may open a COView object. However, I am only able to open a COView object with COView::OpenView using MS CCE. I can't use template functions or COView::OpenWithCmnd to open a COView object with MS CCE. Why?
           You are right! Currently you can only use COView::OpenView to open a COView object because of limitations of current version of MS CCE. Additionally, you can't use COView::OpenRowset to apply a view to a rowset either. We hope MS continue to improve its MS CCE functionality.

5. BLOB as in-memory or BLOB as storage? Which method is better to be used for accessing a BLOB?
           A BLOB can be accessed as an in-memory data, an array of bytes, or retrieved as a single unit, a storage object. OleDBPro supports both the two methods. See the examples BLOBs and AOTBLOB. According to our experience and as shown in the two examples, it is simpler, more convenient and more straight to use BLOB as in-memory. Additionally, the first method may be faster for most of relational DBMS providers. It seems to us that relational DBMS providers internally transfer a storage object from and into an array of bytes at the client side, which costs a fraction of time.