diff --git a/library/think/db/builder/Mysql.php b/library/think/db/builder/Mysql.php
index 4aac4424..5bc9d03b 100644
--- a/library/think/db/builder/Mysql.php
+++ b/library/think/db/builder/Mysql.php
@@ -47,6 +47,9 @@ class Mysql extends Builder
             $key = '`' . $key . '`';
         }
         if (isset($table)) {
+            if (strpos($table, '.')) {
+                $table = str_replace('.', '`.`', $table);
+            }
             $key = '`' . $table . '`.' . $key;
         }
         return $key;