修改活动表以使键不唯一 [英] Alter a live table to make a key non-unique

问题描述

我看到了与此有关的其他一些问题，但它们不是MySQL.

该数据库是一个实时数据库，因此我不想删除并重新创建该表.我只是想使一列不再唯一，它本质上不太宽松，因此不会引起任何问题.

解决方案

如果使用UNIQUE子句将您的列定义为唯一，则使用:

ALTER TABLE mytable DROP INDEX constraint_name

，或者，如果您的约束是隐式命名的，

ALTER TABLE mytable DROP INDEX column_name

如果使用PRIMARY KEY子句将其定义为唯一，请使用:

ALTER TABLE mytable DROP PRIMARY KEY

但是，请注意，如果表为InnoDB，则删除PRIMARY KEY会导致表的隐式重新创建并重建所有索引，这将锁定该表并可能使它在相当长的时间内无法访问. /p>

I saw some other questions related to this, but they were not MySQL.

The database is a live database, so I don't want to delete and recreate the table. I simply want to make a column no longer unique, which is less permissive in nature so it shouldn't cause any problems.

解决方案

If your column was defined unique using UNIQUE clause, then use:

ALTER TABLE mytable DROP INDEX constraint_name

, or, if your constraint was implicitly named,

ALTER TABLE mytable DROP INDEX column_name

If it was defined unique using PRIMARY KEY clause, use:

ALTER TABLE mytable DROP PRIMARY KEY

Note, however, that if your table is InnoDB, dropping PRIMARY KEY will result in implicit recreation of your table and rebuilding all indexes, which will lock the table and may make it inaccessible for quite a long time.

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