Why am i getting this error? WordPress database error: [Query was empty]

Question

I am using Wordpress 3.4.2, latest version! I have no plugins installed except the one that I am writing.

So Here's the deal, I'm reading a json feed and i'm trying to import its content into a table that i created in my wordpress database. I've used a similar set of code in another plugin that I wrote and it works fine there. I do not understand why it does not work here.

When i run this different plugin that i am writing i am get the dreaded and oh so clear "WordPress database error: [Query was empty]".

Here is my code...

// Setup the array
$values = array();

foreach ($bugs as $bug) {
 $status_text = $bug['text'];
 $tContent = htmlSpecialChars(html_entity_decode($status_text));
 $imported = 2;

 [ shortened to keep this post short, but other values are listed here. ]


  // for the values insert part
  $values[] = '("'.$tContent. '", "'.$imported.'")';
}

if(is_array($values)) {
   echo "<hr><strong>WHAT TO IMPORT?</strong><br/>";
   var_dump(implode(',', $values));
}

This output all of the values as expected. Everything is wrapped in parentheses and seperate by a comma.

Then i do this...

global $wpdb;
$table_name = $wpdb->prefix . "bugtbl_temp";

$sql = $wpdb->prepare (
    "INSERT INTO $table_name
    (`post_content`, `imported`)
    VALUES ". implode(',', $values) . " ON DUPLICATE KEY UPDATE imported = 1"
);
$wpdb->query($sql); // execute query


$wpdb->print_error(); // any errors?
$wpdb->last_query; // show the qry
$wpdb->flush(); // cleanup

And then when i run this function I get the "WordPress database error: [Query was empty]" and nothing is imported into my table.

I saw on here one other guy was having problems with $wpdb->prepare. Am I using it incorrectly?

Answer 1

I saw on here one other guy was having problems with $wpdb->prepare. Am I using it incorrectly?

As you can read in the Codex, it's a simple No.

You have to use it like sprintf/printf(). The only allowed inputs are

• string: %s
• digit: %d

Example

$sql = $wpdb->prepare( 
     "
        INSERT INTO %s
        (`post_content`, `imported`)
        VALUES %s
        ON DUPLICATE KEY UPDATE imported = 1
     "
    ,"{$wpdb->prefix}bugtbl_temp"
    ,implode( ',', $values )
);

Disclaimer: The ↑ shown query, doesn't necessarily mean that it will give you results, just because you then used the $wpdb->prepare() right.

Answer 2

I've had the same error when I forgot to add the last numeric argument in an update statement; Check that your arguments match up with the replacement tokens.

Say you have an sql string like this:

$sql = "update mytable set column1 = %s where id  = %d;"
$wpdb->query($wpdb->prepare($sql, 'foobar'));

The solution is obviously to add the id

$id = 5;
$wpdb->query($wpdb->prepare($sql, 'foobar', $id));