ACCESS FEED: Re: [MS_AccessPros] Union query truncating results

Senin, 12 Oktober 2015

Re: [MS_AccessPros] Union query truncating results

nice to know -- thanks for sharing

warm regards,
crystal

~ have an awesome day ~

On 10/12/2015 11:17 AM, John Viescas JohnV@msn.com [MS_Access_Professionals] wrote:

Ray-

Yup. UNION causes the database engine to use indexes to weed out the duplicates. An index value cannot contain more than 256 characters, so any longer fields get truncated. UNION ALL just does a straight fetch from the two (or more) recordsets without using an index or doing any truncation. You'll find that DISTINCT also truncates for the same reason.

John Viescas, Author

Microsoft Access 2010 Inside Out

Microsoft Access 2007 Inside Out

Microsoft Access 2003 Inside Out

Building Microsoft Access Applications

SQL Queries for Mere Mortals

http://www.viescas.com/

(Paris, France)

On Oct 12, 2015, at 6:59 PM, rayfrew@gmail.com [MS_Access_Professionals] <MS_Access_Professionals@yahoogroups.com> wrote:

Hi everyone

I was trying to link 2 Outlook folders and create a merged view so that emails saved in the 2 folders could be viewed on a form. Using the wizard I created Outlook folders in Access as linked tables. My next step was to select the data using a union query e.g.

Select EmailFrom, EmailSubject, EmailMessage from table1

Union

Select EmailFrom, EmailSubject, EmailMessage from table2

sadly the EmailMessage content was truncated - yet the data was there.

By changing the query to Union All it solved the problem - all data present an correct. Three letters make all the difference.

Still learning.

Ray