Comparing for Duplicate rows

My "imported or linked" database has duplicate rows. The
(columns) fields I need to extract only need one row for
each entry in the invoice field. Please tell me where to
find out (a) how to compare one table to another, and if
possible how to auto highlite (or select) which columns
are different information (90 columns).
(b) know if there is a module or selection in program to
remove all but one row in a field that has dups.
Thanks for your help. I'm willing to buy a book, etc.
anything that will help me understand comparisons. I did
not create the imported db.
sue

Hi Sue,

If you just want to retrieve single rows from tables that have
duplicates, use constructions like

SELECT DISTINCT
and
SELECT TOP 1

To identify duplicate rows, use the Find Duplicates query wizard, which
lets you specify which columns to compare. If necessary you can edit the
SQL produced by the wizard to fine-tune it.

To compare tables, you can create a query that joins them on the
relevant fields (to see what records they have in common); use the Find
Unmatched query wizard; or various other kinds of queries.

There's a very good book on using SQL to extract and compare data. From
memory, the authors are Hernandez and Viescas and the title is something
like SQL for Mere Mortals (my copy's in the office and I'm at home).


On Thu, 13 May 2004 10:17:31 -0700, "rsue"
wrote:

My "imported or linked" database has duplicate rows. The
(columns) fields I need to extract only need one row for
each entry in the invoice field. Please tell me where to
find out (a) how to compare one table to another, and if
possible how to auto highlite (or select) which columns
are different information (90 columns).
(b) know if there is a module or selection in program to
remove all but one row in a field that has dups.
Thanks for your help. I'm willing to buy a book, etc.
anything that will help me understand comparisons. I did
not create the imported db.
sue

--
John Nurick [Microsoft Access MVP]

Please respond in the newgroup and not by email.