SQL query - finding non-matching data in a table

Please start any new threads on our new site at https://forums.sqlteam.com. We've got lots of great SQL Server experts to answer whatever question you can come up with.

All Forums

General SQL Server Forums

New to SQL Server Programming

SQL query - finding non-matching data in a table

Author

Topic

barnsley
Starting Member

34 Posts

Posted - 2011-06-22 : 06:14:02

I have 2 tables and would like to display only the non-matching data in 1 of the tables which doesn't appear in the 2nd table.

e.g.
Table1 Table2
Rod         Rod
Jane      Jane
Freddy     Sam
xxx

So my query should find 1 record - 'Sam'.

I can display matching records, but not the ones which don't match.
Table1 is much larger than the other - and it displays every record in Table1 and multiple entries from Table2 (becasue they aren't equal at some point).

Code for displaying matching records:

SELECT     TOP 100 PERCENT Table1.Name AS Tbl1Name, Table2.Name AS Tbl2Name
FROM         Table2 INNER JOIN
                      Table1 ON Table2.Name = Table1.Name

(to display non-matching records - I tried using <> instead of = )
thanks in advance.

mark.

sunitabeck
Master Smack Fu Yak Hacker

5155 Posts

Posted - 2011-06-22 : 06:58:40

If you are looking for rows in Table1 that are not in Table2, you can do this:

SELECT
	Table1.Name
FROM
	Table1
WHERE
	NOT EXISTS
	(
		SELECT * FROM Table2
		WHERE Table2.Name = Table1.Name
	)

If you want to find names that are in one table but not in the other, you can use a full join.


SELECT
	Table1.Name AS Tbl1Name,
	Table2.Name AS Tbl2Name
FROM
	Table2
	FULL JOIN Table1
		ON  Table2.Name = Table1.Name
WHERE
	Table1.Name IS NULL
	OR Table2.Name IS NULL;

In a similar way, the first query could be rewritten to use a left join.

barnsley
Starting Member

34 Posts

Posted - 2011-06-22 : 08:13:13

thanks sunitabeck,
that works!

mark.

jcelko
Esteemed SQL Purist

547 Posts

Posted - 2011-06-23 : 00:31:19

Please post real DDL and not narrative or your own personal programming language. Learn to use ISO-11179 rules for the data element names, avoid needless dialect and use ISO-8601 temporal formats, codes and so forth. Please tell us what SQL product and release you are using. Tell us if you can change the DDL or if you are stuck with it.

Basic set operators from junior high school?

(TableA
UNION
TableB) AS Everything
EXCEPT
(TableA
INTERSECT
TableB) AS CommonStuff

--CELKO--
Books in Celko Series for Morgan-Kaufmann Publishing
Analytics and OLAP in SQL
Data and Databases: Concepts in Practice
Data, Measurements and Standards in SQL
SQL for Smarties
SQL Programming Style
SQL Puzzles and Answers
Thinking in Sets
Trees and Hierarchies in SQL

Subscribe to SQLTeam.com

SQLTeam.com Articles via RSS

SQLTeam.com Weblog via RSS

- Advertisement -

Resources