How to alter an existing column to default to the current time on insert, in MySQL?
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I'm trying to change the existing column "time_sent" to default to the time during insertion. My SQL is:

    ALTER TABLE `email_history` alter `time_sent` set DEFAULT CURRENT_TIMESTAMP

I'm getting this error though:

     MySQL said: 
    #1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'CURRENT_TIMESTAMP' at line 1 

I've read the documentation and other (similar, but not identical) examples, and no luck.

My version of MySQL is 5.0.67 I believe.