Comments on: Adding a Unique Constraint on a Table with Duplicate Data

By: Artículos destacados de Agosto | cambrico.net

Artículos destacados de Agosto | cambrico.net — Sat, 06 Sep 2008 10:30:30 +0000

[…] una constraint única cuando hay duplicados en una tabla, en el blog de The pythian group (en […]

By: Log Buffer #110: A Carnival of the Vanities for DBAs

Log Buffer #110: A Carnival of the Vanities for DBAs — Fri, 15 Aug 2008 16:46:31 +0000

[…] Here on the Pythian Group Blog, Nicklas Westerlund demonstrates adding a unique constraint on a table with duplicate data. […]

By: Nicklas Westerlund

Nicklas Westerlund — Sat, 09 Aug 2008 15:30:10 +0000

Thanks all for your opinions. Is there any other subject you’d like me to blog about or explain in further detail?

By: René Leonhardt

René Leonhardt — Sat, 09 Aug 2008 10:40:07 +0000

DELETE FROM t1
USING
post1164 AS t1
INNER JOIN post1164 AS t2
USING(b)
WHERE
t1.a < t2.a;

By: Scott Noyes

Scott Noyes — Sat, 09 Aug 2008 03:43:41 +0000

DELETE FROM t1
USING
post1164 AS t1
LEFT JOIN post1164 AS t2 ON
t1.b = t2.b
AND t1.a < t2.a
WHERE
t2.a IS NOT NULL;

By: akira

akira — Fri, 08 Aug 2008 21:09:01 +0000

CREATE TABLE tmp1164 LIKE post1164;
ALTER TABLE tmp1164 ADD UNIQUE KEY idx1(a);
INSERT IGNORE INTO tmp1164 SELECT * FROM post1164 ORDER BY a DESC 
RENAME TABLE post1164 TO old1164, tmp1164 TO post1164; SELECT * FROM post1164