Bug #7479 | Duplicate entries allowed with UNIQUE index when values are NULL | ||
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Submitted: | 22 Dec 2004 12:18 | Modified: | 18 Oct 2005 5:54 |
Reporter: | Frederic linot | Email Updates: | |
Status: | Duplicate | Impact on me: | |
Category: | MySQL Server: MyISAM storage engine | Severity: | S3 (Non-critical) |
Version: | 4.0.21-standard | OS: | Linux (linux) |
Assigned to: | CPU Architecture: | Any |
[22 Dec 2004 12:18]
Frederic linot
[22 Dec 2004 12:55]
MySQL Verification Team
Thank you for taking the time to write to us, but this is not a bug. Please double-check the documentation available at http://www.mysql.com/documentation/ and the instructions on how to report a bug at http://bugs.mysql.com/how-to-report.php Additional info: From the MySQL manual: In MySQL, a UNIQUE index is one in which all values in the index must be distinct. An error occurs if you try to add a new row with a key that matches an existing row. The exception to this is that if a column in the index is allowed to contain NULL values, it can contain multiple NULL values. This exception does not apply to BDB tables, for which indexed columns allow only a single NULL.
[18 Oct 2005 5:54]
Sergei Golubchik
see also BUG#6829