RE: VB.Net (ADO): Thoughts on Copying 7 tables to 1 table
From: NIL (NIL_at_discussions.microsoft.com)
Date: 10/23/04
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Date: Sat, 23 Oct 2004 09:31:02 -0700
You can write a QUERY that uses UNION and execute it to copy all the data in
7 Tables to the new table.
select col1, col2, col3 from table1
UNION
select col1, col2, col3 from table2
UNION
..
..
select col1, col2, col3 from table7
"Mr. B" wrote:
> 2 Part Question:
>
> I've a VB.net application where I read information from 7 Tables in a MS
> Access Db. There is a performance hit when this happens (about a 1-2 second
> hit per table). So I'm going to combine the relavent parts of each table into
> a single table in a "new' MDB file.
>
> I've experimented with this and found that the best way that I can see is to
> gather the information from each table into an Array and then dump that info
> into my new MDB file. I want all the 7 tables starting with the FIRST row in
> the new table.
>
> I first get the number of rows for a table, re-dim my array and gather the
> info. Then I repeat for the next table - I compare table row lengths to make
> sure my Array does not get smaller than the maximum table row found.
>
> All appears to work fine.
>
> Question #1:
>
> Can someone suggest a better way (if there is one) to take the "selected"
> columns from a single MDB (having 7 tables) into a new single MDB with 1
> table. I tried reading each of the 7 tables into my new MDB, but this doesn't
> work as each table adds new rows past the previous table information.
>
> Question #2:
> Every now and then, I find one of my columns (about mid way down) has a bunch
> of NULL cells when the data should be continuous in the column. I run the
> application again (maybe a third time) and all is OK. All the other columns
> are OK (and the code is similar). A head scratcher for me. Any thoughts?
>
> Thanks in advance.
>
> Regards,
>
> Bruce
>
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