diff --git a/lualib/skynet/db/mysql.lua b/lualib/skynet/db/mysql.lua
index 44b58a65..afa6e229 100644
--- a/lualib/skynet/db/mysql.lua
+++ b/lualib/skynet/db/mysql.lua
@@ -841,6 +841,9 @@ local function _get_datetime(data, pos)
     if len == 7 then
         year, month, day, hour, minute, second, pos = string.unpack("<I2BBBBB", data, pos)
         value = strformat("%04d-%02d-%02d %02d:%02d:%02d", year, month, day, hour, minute, second)
+    elseif len == 4 then
+        year, month, day, pos = string.unpack("<I2BB", data, pos)
+        value = strformat("%04d-%02d-%02d %02d:%02d:%02d", year, month, day, 0, 0, 0)
     else
         value = "2017-09-09 20:08:09"
         --unsupported format