[Okta Webinar] Learn how to a build a cloud-first strategyRegister Now

x
  • Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 1235
  • Last Modified:

exclude records in one table from another table

I have a table with certain customers that should be excluded from mailing.  How do I join the full table to this table to provide a list with just those who should get the mailing?  Thank you in advance for your help.
0
clballas
Asked:
clballas
  • 3
  • 2
1 Solution
 
Leigh PurvisDatabase DeveloperCommented:
SELECT *
FROM tblCustomers
WHERE CustomerID Not In (SELECT CustomerID FROM tblCostNoMail)

or

SELECT *
FROM tblCustomers
    LEFT JOIN tblCostNoMail ON tblCustomers.CustomerID = tblCostNoMail.CustomerID
WHERE tblCostNoMail.CustomerID Is Null
0
 
rockiroadsCommented:
Perfect SQL from LPurvis

An alternative idea

Why dont u have a flag on your main table. This indicates whether they get included or not

Then u can just use this flag value


Doesnt answer your question but gives an alternative design and so the SQL is easier for you.

Oh well
0
 
clballasAuthor Commented:
LPurvis,

Both ways seem to work.  Any reason to choose one over the other?

--clballas

0
Free recovery tool for Microsoft Active Directory

Veeam Explorer for Microsoft Active Directory provides fast and reliable object-level recovery for Active Directory from a single-pass, agentless backup or storage snapshot — without the need to restore an entire virtual machine or use third-party tools.

 
Leigh PurvisDatabase DeveloperCommented:
Opinion varies.
There's every chance that Jet would create an execution plan the same way for either.
It used to be felt that the Join would operate more efficiently - but as stated above this isn't necessarily so.
(I can't remember testing in recent history - but as a general rule I'll prefer the Join... and use In when it's required).

Simple answer - run them both - see if one's slightly faster. :-)
(It could well vary from recordset to recordset).
0
 
clballasAuthor Commented:
Outstanding, clear answer! Thanks so very much!
0
 
Leigh PurvisDatabase DeveloperCommented:
You're very welcome.  :-)
0

Featured Post

NEW Veeam Agent for Microsoft Windows

Backup and recover physical and cloud-based servers and workstations, as well as endpoint devices that belong to remote users. Avoid downtime and data loss quickly and easily for Windows-based physical or public cloud-based workloads!

  • 3
  • 2
Tackle projects and never again get stuck behind a technical roadblock.
Join Now