diff --git a/FreeSql/Internal/CommonProvider/UpdateProvider.cs b/FreeSql/Internal/CommonProvider/UpdateProvider.cs
index 5e786eff..9117e0c6 100644
--- a/FreeSql/Internal/CommonProvider/UpdateProvider.cs
+++ b/FreeSql/Internal/CommonProvider/UpdateProvider.cs
@@ -655,6 +655,11 @@ namespace FreeSql.Internal.CommonProvider
             if (col.Attribute.MapType == col.CsType) val = value;
             else val = Utils.GetDataReaderValue(col.Attribute.MapType, value);
             _set.Append(", ").Append(_commonUtils.QuoteSqlName(col.Attribute.Name)).Append(" = ");
+            if (value == null)
+            {
+                _set.Append("NULL");
+                return;
+            }
 
             var colsql = _noneParameter ? _commonUtils.GetNoneParamaterSqlValue(_params, "u", col, col.Attribute.MapType, val) :
                 _commonUtils.QuoteWriteParamterAdapter(col.Attribute.MapType, _commonUtils.QuoteParamterName($"p_{_params.Count}"));