How to find duplicated values in MySQL (or/and probably any other RDBM)
As an example I take one real (almost) table I have in my db.
Structure is very simple :
Table name: “words”, field “filename” name of the file and “words” just some information about each file.
+—————–+———————+
| filename | words |
+—————–+———————+
Suddenly we had a few files with exactly same name and I could find them, so… SQL here to help!
SELECT count( * ) AS num, filename
FROM words
GROUP BY filename
HAVING count( * ) > 1
Simple and quick explanation: we group output by “filename” and count output, if output amount more then 1, display it, together with filename.
PS: why we had duplicated fields? We had two fields with NULL values inside. Stupid import from MS Access…
Posted on February 16, 2009 at 14:55 by admin · Permalink
In: English, sql · Tagged with: dublicated values, mysql, sql
In: English, sql · Tagged with: dublicated values, mysql, sql