Improve orderByNullsLast SQL generation.

Add string replace option for column and direction.

Author: yajra

src/QueryDataTable.php

@@ -690,7 +690,11 @@ protected function getNullsLastSql($column, $direction)
     {
         $sql = $this->config->get('datatables.nulls_last_sql', '%s %s NULLS LAST');
 
-        return sprintf($sql, $column, $direction);
+        return str_replace(
+            [':column', ':direction'],
+            [$column, $direction],
+            sprintf($sql, $column, $direction)
+        );
     }
 
     /**

src/config/datatables.php

@@ -64,10 +64,10 @@
     ],
 
     /*
-     * Nulls last sql pattern for Posgresql & Oracle.
-     * For MySQL, use '-%s %s'
+     * Nulls last sql pattern for PostgreSQL & Oracle.
+     * For MySQL, use 'CASE WHEN :column IS NULL THEN 1 ELSE 0 END, :column :direction'
      */
-    'nulls_last_sql' => '%s %s NULLS LAST',
+    'nulls_last_sql' => ':column :direction NULLS LAST',
 
     /*
      * User friendly message to be displayed on user if error occurs.