php and mysql the state of the art...which extension?

What are the differences between libraries and mysql mysqli pdo to connect with PHP? What should I stu开发者_开发技巧dy for the future?

Thanks a lot.

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I'd recommend PDO, because if you change to a different DB at a later day, or if you wish to use a different DB in another project, then at least you won't have to learn another API, since PDO supports a lot of the more popular DBMSs.