diff --git a/library/think/db/Builder.php b/library/think/db/Builder.php
index 0e8a3c45..825d54b2 100644
--- a/library/think/db/Builder.php
+++ b/library/think/db/Builder.php
@@ -113,14 +113,14 @@ abstract class Builder
             } elseif (is_null($val)) {
                 $result[$item] = 'NULL';
             } elseif (is_array($val) && !empty($val)) {
-                switch ($val[0]) {
+                switch (strtolower($val[0])) {
                     case 'inc':
                         $result[$item] = $item . '+' . floatval($val[1]);
                         break;
                     case 'dec':
                         $result[$item] = $item . '-' . floatval($val[1]);
                         break;
-                    default:
+                    case 'exp':
                         throw new Exception('not support data:[' . $val[0] . ']');
                 }
             } elseif (is_scalar($val)) {