WordPress $ wpdb-> get_results（）没有返回值

Question

I'm in the process of looking at a WordPress plugin (never used WordPress before) and am running into an issue trying to execute a very basic SELECT statement against the database.

Ex:

$sql = "SELECT * FROM wp_posts";
$result = $wpdb->get_results( $sql );
var_dump($result);
echo($result);

This doesn't display anything even though my wp_posts table has a couple hundred rows. Can someone tell me what I'm missing? Thanks.

Answer 1

This may or may not be the issue, but often, prefixes cause trouble and it is not recommended to hardcode tables in.

Secondly, can you output the value of $wpdb? If not, and this is most likely the problem, you don't have access to $wpdb in your scope.

Use global $wpdb if you are executing this within a function.

$sql = "SELECT * FROM $wpdb->posts";
$result = $wpdb->get_results( $sql );