$wpdb->prepare error after WordPress update [duplicate]

Because you’re missing second argument, for more information see this post – http://make.wordpress.org/core/2012/12/12/php-warning-missing-argument-2-for-wpdb-prepare/.

Also you’re doing it wrong, for security reason you shouldn’t pass variables into query directly that’s why you should use prepare() method – see Codex for usage info.

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