How do I drop a primary key in MySQL?

I have a primary key name idnumber. how can I remove its primary k开发者_运维技巧ey in mysql

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This should work for you, but are you sure you want to drop the primary key?

ALTER TABLE tablename DROP PRIMARY KEY;

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Help on alter table syntax here

Why would you want to drop the the primary key? If you created it by mistake then you can change it by

alter table T drop primary key, add primary key (C);

Where T is the table name and C is the column containing the correct primary key

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You'd need to drop and create a new primary key if you currently have it on AUTOINCREMENT, something like this:

ALTER TABLE table DROP PRIMARY KEY, ADD PRIMARY KEY(your_column);