I have a form with multiple select values that I would like to store in a database. I have named the array fields: area_mls[] and type_mls[]. This is the code I'm using...

  $insertSQL = sprintf("INSERT INTO mlsArea_mls (name_mls, state_mls, realtorID_mls, area_mls, type_mls)
  VALUES (%s, %s, %s,

  '" . join(",",$_POST["area_mls"]). "',
  '" . join(",",$_POST["type_mls"]). "'
  )",

                       GetSQLValueString($_POST['name_mls'], "text"),
                       GetSQLValueString($_POST['state_mls'], "text"),
                       GetSQLValueString($_POST['realtorID_mls'], "int"));

I get the following error messages...

Warning: join(): Bad arguments. in ../public_html/mlsArea.php on line 41

Warning: Cannot modify header information - headers already sent by (output started at ../public_html/mlsArea.php:41) in ../public_html/mlsArea.php on line 57

I'm thinking it's because the datatypes aren't correct for this type of join statement. It worked for me with a text field, but now I'm trying to store the id's of the values in an int field in mysql database.

I'm sure it's something simple, I'm just not familiar enough with PHP to know how to make it work.

Thanks for any help you can provide.

Most likely, your second argument in the join, i.e. your $_POST["area_mls"] isn't an array. The probable reason for this is in the name for your select element.

If you've got a select element like this:
then in the $_POST['selList'] variable, you'll just have a single element, which is the last item selected in 'selList', even if there are multiple items selected.

To get around this, do the following:
This will mean that $_POST['selList'] is always an array, containing all selected items (it is still an array even if only one item was selected).

The only problem arises when no items are selected. In this case, $_POST['selList'] won't exist. What you need to do is use the array_key_exists function to check for the existence of the item you're after.