Just created a WordPress Table can’t get $wpdb get row to work – need help

You’re doing it wrong …

Don’t use a custom table for this!

What you can do instead is store this information in user meta (in the wp_usermeta table).

Let’s say you want to store last_slide=3 in the user meta table. You’d use the following:

update_user_meta( $user_id, 'last_slide', 3 );

To get this back, you’d call:

get_user_meta( $user_id, 'last_slide', true );

I recommend doing it this way so you don’t try to reinvent the wheel with a custom table and custom queries.

Now to answer the actual question …

In your code, you try to get the value back out of your custom table with this call:

$thenbr = $wpdb->get_row( $wpdb->slideshow( "SELECT * FROM $wpdb->slideshow WHERE user = "admin"" ) );

That basically won’t work. The $wpdb object has no method called slideshow(), so calling $wpdb->slideshow() will throw an error, not return any data. Re-read the Codex article on using this object to select a row.

What you want instead would be along the lines of:

$thenbr = $wpdb->get_row( "SELECT * FROM $wpdb->slideshow WHERE user="admin"" );

But again, I highly advise against using custom queries and custom tables!