在Wordpress中的SQL语句中的RTRIM

Question

I'm trying to check a filename in a sql statement, that I'm using in PHP, in a wordpress template I'm building.

Bascially I'm trying to use LTRIM to only bring back images that have _a on the end.

eg I have a bunch of images in a series of folders

• clientone_a.jpg
• clienttwo_b.jpg
• ...etc...

this is what Im using at the moment but it doesnt work;

$query = "
    SELECT F.field_value, P.alttext, P.filename, P.description, p.galleryid, 
        G.path 
    FROM wp_nggcf_field_values F, 
        wp_ngg_pictures P, 
        wp_ngg_gallery G 
    WHERE F.fid=1 
        AND (F.field_value='".$data."') 
        AND F.pid = P.PID 
        AND P.galleryid = G.gid 
        AND LTRIM(P.filename,'_') = '_a.jpg'
";

$caseStudiesResults = $wpdb->get_results($query);

It's just the last LTRIM(P.filename,'_') = '_a.jpg' that is the problem, without that it bring back all the images, and I'm after bringing back the _a one only.

Any ideas on where I'm going wrong ?

Thanks

Answer 1

The problem is that you're using the wrong function. LTRIM() simply removes leading spaces. What you're looking for is SUBSTRING_INDEX()

AND SUBSTRING_INDEX(P.filename, '_', -1) = 'a.jpg'

The -1 tells it to return everything to the right of the final delimiter ( -2 would be everything to the right of the 2nd to last delimiter, 1 would be everything to the left of the first, etc)...

Edit: As far as testing it, you can test string functions by doing this:

SELECT SUBSTRING_INDEX('test_a.jpg', '_', -1) = 'a.jpg'

Run that, and see if it works (it did for me). By putting static values, you can try it out without needing to run the whole big query...

Answer 2

替代substring_index

select substring('clientone_a.jpg', -6)='_a.jpg';