🚀 go-pugleaf

On 3 Feb 2003 15:04:53 -0800, Don Wilcox wrote:

>Is it possible to create a new .mdb file from within a C++ program? I can use SQL to create tables, but verything I have found requires an >existing file.

You need to import the ADO extensions type library.  I don't recall the exact
name, but it's something like "Microsoft ActiveX Data Objects 2.7 DDL and
Security".  You'll know the correct one by which components it includes.  You
need TCatalog as the bare minimum to create the Access .mdb file.  Since
there are already TTable and TColumn classes in VCL, when importing that
library, I renamed each component from T<whatever> to ADO<whatever>.  

I found that creating a table via SQL results in the table data itself taking
up about twice as much space as it's supposed to, and taking twice as long to
search through.  I don't know why this is, but when the same exact table
definition is created via ADOX, the table size and speed is normal.  Needless
to say, this is after compacting that the size comparison is made, since
creating and populating an Access database will give you a file almost twice
as large as it is after compacting.  

As an example, a table with about 230,000 records (around 600 bytes per
record) ended up with  a total compacted database size of about 270MB (table
and a few indexes).  That's when the table is created via SQL.  When the
table is created via ADOX, the final compacted database size is around 150MB.
 Doing a search that causes a table scan takes twice as long (if not longer)
on the SQL-created table versus the ADOX-created table.  Everything is
identical except the mechanism used to create the table definition.  In both
cases, the indexes were created via SQL.  

If you're not dealing with large quantities of data, it may not matter.


--
 - Mike

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