Question

Trying to do a search and replace using php/mysql. I do this in specified table headers/columns. it works fine when my search term has a value. However i want to search for an empty field in a specified column and replace with a value. it fails to do a search and replace when my search term is an empty string. Any help?

$SearchAndReplace_header = isset($_POST['SearchAndReplace_header']) ? $_POST['SearchAndReplace_header'] : "";

$SearchAndReplace_search_term = isset($_POST['SearchAndReplace_search_term']) ? $_POST['SearchAndReplace_search_term'] : "";

$SearchAndReplace_replace_with = isset($_POST['SearchAndReplace_replace_with']) ? $_POST['SearchAndReplace_replace_with'] : "";

//foreach($fields as $key => $val) {
 //   if($SearchAndReplace_header == "all" || ($SearchAndReplace_header == $val)) {
        // replace column value with parameter value
        $sql = "UPDATE ".$table_name." SET ".$val." = REPLACE(".$val.",'".$SearchAndReplace_search_term."','".$SearchAndReplace_replace_with."')";                                              
        $db->query($sql);
   // }
  // }

Answer 1

You can’t do a replace on an empty field, you’ll have to set the field directly.

UPDATE table 
SET column = 'value' 
WHERE column = '' or column is null 

If you want to cover both cases in a single query, you could do something like this:

UPDATE table 
SET column = CASE 
                 WHEN column IS NULL OR COLUMN = '' 
                     THEN 'replace' 
                 ELSE
                      REPLACE(column, 'find', 'replace')
             END CASE