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 Adding IDENTITY column = inconsistent results!!

Author  Topic 

Barry Seymour
Starting Member

2 Posts

Posted - 2015-05-06 : 20:25:22
I have a really STRANGE issue that's driving me nuts. I am getting inconsistent results when BULK INSERTING data from a tab-delimited text file. As part of my testing, I run the same code on the same file again and again, and I get different results every time! I get this on SQL 2005 and SQL 2012 R2.

We have an application that imports data from a spreadsheet. The sheet contains section headers with account numbers and detail rows with transactions by date:

AAAA.1234 /* (account number)*/
1/1/2015 $150 First Transaction
1/3/2015 $24.233 Second Transaction
1/1/2015 $350 Third Transaction
1/3/2015 $24.233 Fourth Transaction

My Import program saves this spreadsheet at tab-delimited text, then I use BULK INSERT to bring the data into a generic table full of varchar(255) fields. There are about 90,000 rows in each day's data; after the BULK INSERT about half of them are removed for various reasons.

I then run a routine that converts and copies those records into another holding table that's a copy of the final destination table. That routine parses though the data, assigning the account number in the section header to each detail row. The goal is to have it end up looking like this:

AAAA.1234 1/1/2015 $150 First Purchase
AAAA.1234 1/3/2015 $24.233 Second Purchase
BBBB.5678 1/1/2015 $350 Third Purchase
BBBB.5678 1/3/2015 $24.233 Fourth Purchase

My technique: I add a RowID column to the table with the IDENTITY (1,1) property. This gives my raw data unique row numbers.

I use a cursor to get the starting RowID for each Account Number: I then use the upper and lower RowIDs to do an INSERT into the final table. The query looks like this:

SELECT RowID, SUBSTRING(RowHeader, 6,4) + '.UBC1' AS AccountNumber
FROM GenericTable
WHERE RowHeader LIKE '____.____%'
Results look like this:

But every time I run the routine, I get different numbers!

Needless to say, my results are not accurate. I get inconsistent results EVERY TIME. It's maddening!

Here is my code, with table, field and account names changed for business confidentiality. I’m open to suggestions; I’m truly stuck. This is a high profile project at my company; any help would be deeply appreciated.

TRUNCATE TABLE GenericImportTable;
BULK INSERT GenericImportTable FROM '\\SERVER\General\Appname\'
SELECT RowID, SUBSTRING(RowHeader, 6,4) + '.UBC1' AS AccountNumber
FROM GenericImportTable
WHERE RowHeader LIKE '____.____%'

Almighty SQL Goddess

38200 Posts

Posted - 2015-05-06 : 20:36:30
Are you relying on the ALTER TABLE ADD IDENTITY to always give you the same order? That's the issue right there. The order in a table is meaningless. Instead, drop the table and then recreate with the identity column. It'll be in the order of the file now.

Tara Kizer
SQL Server MVP since 2007
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Barry Seymour
Starting Member

2 Posts

Posted - 2015-05-07 : 00:08:31
Thanks, Tara. Yeah, that was my assumption.

Now that I know my assumption is incorrect, I know what to do. My VB app opens the worksheet and saves it as Tab-delimited text -- I can add a bit that inserts a row number to the text file. At that point my BULK INSERT will result in a table with properly numbered rows. The rest will work as originally desired.

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