Solved

Query to find delta / exceptions between 2 tables

Posted on 2014-12-04
14
179 Views
Last Modified: 2014-12-04
I have two tables (tableA, tableB) which basically contain the same data.  The key between the 2 is serial_number.  I need a query to return the delta between the 2 tables.

TableA contains all the data that should be in TableB but that is not the case.  I need to determine which serial numbers from TableA are not appearing in TableB.
0
Comment
Question by:szadroga
  • 6
  • 2
  • 2
  • +3
14 Comments
 
LVL 15

Expert Comment

by:Haris Djulic
ID: 40480722
Hello,

try to use EXCEPT command..
SELECT *
FROM Table A
EXCEPT
SELECT *
FROM TableB

Open in new window

0
 
LVL 24

Expert Comment

by:Phillip Burton
ID: 40480738
SELECT serial_number
FROM tableA
EXCEPT
SELECT serial_number
FROM tableB
0
 

Author Comment

by:szadroga
ID: 40480744
great, so is that basically a translation of

select * from TableA where SERIAL_NUMBER does not equal (select serial_number from TableB);
0
NAS Cloud Backup Strategies

This article explains backup scenarios when using network storage. We review the so-called “3-2-1 strategy” and summarize the methods you can use to send NAS data to the cloud

 

Author Comment

by:szadroga
ID: 40480760
I want to return more fields in the query, not just serial_number but serial_number is the field I need to base the "delta" logic on.
0
 
LVL 24

Expert Comment

by:Phillip Burton
ID: 40480768
I don't think either of ours are that exactly.

Haris compares the entirety of all of the fields, and only where all the fields are identical in both tables for a particular row, then exclude that.

Mine shows only the serial_number, and excludes tableB's serial numbers; it doesn't show all the fields.

If you want to show everything (as you have said "Select *"), then

select * from TableA where SERIAL_NUMBER not in (select serial_number from TableB);
0
 
LVL 47

Accepted Solution

by:
Vitor Montalvão earned 500 total points
ID: 40480781
I prefer the NOT EXISTS clause:
SELECT *
FROM TableA
WHERE NOT EXISTS (SELECT 1 
              FROM TableB
              WHERE TableB.serial_number=TableA.serial_number)

Open in new window

0
 
LVL 35

Expert Comment

by:PatHartman
ID: 40480861
Or, you can use a left join.
Select *
From tblA Left Join tblB On tblA.SerialNumber = tblB.SerialNumber
Where tblB.SerialNumber is Null;

"EXCEPT" is not valid Access SQL Syntax.
0
 

Author Comment

by:szadroga
ID: 40480884
Vitor,

What does the SELECT 1 represent in the sub SELECT query?
0
 
LVL 47

Expert Comment

by:Vitor Montalvão
ID: 40480925
SELECT clause needs at least a column or value. 1 is a constant value so it's used to avoid access to data. It's an old trick ;)
Could be SELECT NULL or SELECT 'A' or any constant value. It's better than a SELECT * since you won't need the sub-query to return any data.
0
 

Author Comment

by:szadroga
ID: 40480928
thanks for clarifying.  I will keep that trick in mind going forward.
0
 
LVL 45

Expert Comment

by:aikimark
ID: 40481227
Is the data in an Access database or a SQL Server database?  If an Access, the EXCEPT keyword is not supported. (confirmed Pat's comment)

You can do this in a single UNION query.
Example:
Select tblA.*, "In A Not In B" As tblDiff
From tblA Left Join tblB On tblA.SerialNumber = tblB.SerialNumber
Where tblB.SerialNumber is Null
UNION ALL
Select tblB.*, "In B Not In A" As tblDiff
From tblB Left Join tblA On tblA.SerialNumber = tblB.SerialNumber
Where tblA.SerialNumber is Null
UNION ALL
Select tblA.*, "Field difference" As tblDiff
From tblA Join tblB On tblA.SerialNumber = tblB.SerialNumber
Where tblA.Field1 <> tblB.Field1
OR tblA.Field2 <> tblB.Field2
OR tblA.Field3 <> tblB.Field3
OR tblA.Field4 <> tblB.Field4

Open in new window

0
 

Author Comment

by:szadroga
ID: 40481329
Currently in Access, but I will move to SQL if the report i am building seems beneficial.
0
 
LVL 35

Expert Comment

by:PatHartman
ID: 40481340
The suggestion I made of the outer join and the suggestion of Not Exists will work in both variants of SQL.  But if you are going to use T-SQL (with a pass-through query) you also have the option of "EXCEPT".
0
 

Author Closing Comment

by:szadroga
ID: 40481429
worked perfectly and at an optimal speed.
0

Featured Post

Simplifying Server Workload Migrations

This use case outlines the migration challenges that organizations face and how the Acronis AnyData Engine supports physical-to-physical (P2P), physical-to-virtual (P2V), virtual to physical (V2P), and cross-virtual (V2V) migration scenarios to address these challenges.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

This article explains how to reset the password of the sa account on a Microsoft SQL Server.  The steps in this article work in SQL 2005, 2008, 2008 R2, 2012, 2014 and 2016.
Ever needed a SQL 2008 Database replicated/mirrored/log shipped on another server but you can't take the downtime inflicted by initial snapshot or disconnect while T-logs are restored or mirror applied? You can use SQL Server Initialize from Backup…
In Microsoft Access, learn how to “cascade” or have the displayed data of one combo control depend upon what’s entered in another. Base the dependent combo on a query for its row source: Add a reference to the first combo on the form as criteria i…
In Microsoft Access, learn different ways of passing a string value within a string argument. Also learn what a “Type Mis-match” error is about.

773 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question