Wordpress update mysql table

Question

I am writing a plugin for Wordpress, which should check if a mysql entry already exists.
If it does not exist Wordpress should insert the entry into the table. This part

Answer 1

UPDATE wp_options SET option_value = replace(option_value, 'http://www.example.com', 'http://localhost/test-site') WHERE option_name = 'home' OR option_name = 'siteurl';
UPDATE wp_posts SET post_content = replace(post_content, 'http://www.example.com', 'http://localhost/test-site');
UPDATE wp_postmeta SET meta_value = replace(meta_value,'http://www.example.com','http://localhost/test-site');

Answer 2

$result = $wpdb->update('westend_areaofficers', array('officerOrder' => $memberOrder,
'officerTitle' => $memberTitle, 'officerName' => $memberName, 'officerPhone' => 
 $memberPhone), array('officerId' => $memberId), array('%d','%s', '%s', '%s'),
 array('%d'));

if($result > 0){
echo "Successfully Updated";
}
else{
  exit( var_dump( $wpdb->last_query ) );
}
$wpdb->flush();

The above solution is what worked for me because using the $wpbd->query($wpbd->prepare()) statement didn't work even when passing in the correct number and string formats.
The purpose of the var_dump() function is to see where the execution of the query went wrong. It prints out the query and values being passed. Of course using the $wpdb->flush() function clears the cache for the next query to execute.

Answer 3

Example:

change user's (whose ID is 546) nicename to Harde_Bande

$execut= $wpdb->query( $wpdb->prepare( "UPDATE $wpdb->users SET user_nicename = %d WHERE ID = %s", "Harde_Bande", 546 ) );
var_dump($execut);

Learn more at: http://codex.wordpress.org/Class_Reference/wpdb#Examples

Answer 4

the value of column time must be enclosed with single quote

$wpdb->query($wpdb->prepare("UPDATE $table_name SET time='$current_timestamp' WHERE userid=$userid"));