Title: Need help writting variable to database
Last modified: August 21, 2016

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# Need help writting variable to database

 *  [WindyPoint](https://wordpress.org/support/users/windypoint/)
 * (@windypoint)
 * [12 years, 1 month ago](https://wordpress.org/support/topic/need-help-writting-variable-to-database/)
 * I’m trying to write a variable to the wp database. I’ve got a forum successfully
   setup so that a user inputs a value, and that value is then serialized and stored
   in a variable.
    However I haven’t been able to get the $wpdb command to work.
   I’m not even sure if it’s being executed or not.
 *     ```
       if (isset($_POST['save_membership_details'])) {
       $wpdb->sql = "UPDATE 'wp_usermeta', SET 'wp_value' = '" .$serial. "', WHERE 'user_id' = '" .$current_user -> ID. "'";}
       $selection = $_POST['membership'];
       $value = array ($selection => true,);
       $serial = serialize($value);
       ```
   

Viewing 4 replies - 1 through 4 (of 4 total)

 *  [catacaustic](https://wordpress.org/support/users/catacaustic/)
 * (@catacaustic)
 * [12 years, 1 month ago](https://wordpress.org/support/topic/need-help-writting-variable-to-database/#post-4864032)
 * Firstly, you’re creating the variables _after_ you’re attempting to add them 
   into the DB… that’s never going to work. You need to get the value and then add
   it into the DB.
 * Secondly, you’re code above updates _every_ meta value for that user as the only
   constraint is the user ID, not the meta key. I’m sure that’s really not what 
   you want.
 * Thirdly, you need to look at the column names. There’s no column called `wp_value`
   in the `wp_usermeta` table, so you’ll get an error becuase your query is trying
   to reference an invalid column name.
 * Forth, you’re wide open to SQL injection attacks becuase you’re not escaping 
   any variables. If you’re going to do it this way, look at [$wpdb->prepare()](https://codex.wordpress.org/Class_Reference/wpdb#Protect_Queries_Against_SQL_Injection_Attacks)
   to find out how to do it correctly.
 * To do it the “right” way you would use [$wpdb->update()](https://codex.wordpress.org/Class_Reference/wpdb#UPDATE_rows).
   Something like this…
 *     ```
       $selection = $_POST['membership'];
       $value = array ($selection => true,);
       $serial = serialize($value);
   
       if (isset($_POST['save_membership_details'])) {
   
           $wpdb->update( array(
               $wpdb->usermeta,
               array(
                   'meta_value' => $serial
               ),
               array(
                   'user_id' => $current_user->ID,
                   'meta_key' => 'your_key_name'
               )
           ));
       }
       ```
   
 * Note that using this function you don’t need to escape the variables as that’s
   done internally by the update() function.
 *  [jon](https://wordpress.org/support/users/adiant/)
 * (@adiant)
 * [12 years, 1 month ago](https://wordpress.org/support/topic/need-help-writting-variable-to-database/#post-4864034)
 * This is not really an answer to your question, but I think you are probably looking
   for this:
    [https://codex.wordpress.org/Function_Reference/add_user_meta](https://codex.wordpress.org/Function_Reference/add_user_meta)
 * Check out the Related section for other relevant functions.
 * (After I wrote this, I see that you have been given a more direct answer)
 *  [catacaustic](https://wordpress.org/support/users/catacaustic/)
 * (@catacaustic)
 * [12 years, 1 month ago](https://wordpress.org/support/topic/need-help-writting-variable-to-database/#post-4864038)
 * jonradio is right too! But, I’d suggest using [update_user_meta()](https://codex.wordpress.org/Function_Reference/update_user_meta)
   as that will add in the value if it doesn’t exist, and update if it exists already.
 *  Thread Starter [WindyPoint](https://wordpress.org/support/users/windypoint/)
 * (@windypoint)
 * [12 years, 1 month ago](https://wordpress.org/support/topic/need-help-writting-variable-to-database/#post-4864275)
 * Thanks for the replies! I’ll post how it goes.

Viewing 4 replies - 1 through 4 (of 4 total)

The topic ‘Need help writting variable to database’ is closed to new replies.

 * In: [Fixing WordPress](https://wordpress.org/support/forum/how-to-and-troubleshooting/)
 * 4 replies
 * 3 participants
 * Last reply from: [WindyPoint](https://wordpress.org/support/users/windypoint/)
 * Last activity: [12 years, 1 month ago](https://wordpress.org/support/topic/need-help-writting-variable-to-database/#post-4864275)
 * Status: not resolved

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