diff --git a/Examples/base_entity/Program.cs b/Examples/base_entity/Program.cs
index 311f0383..502f11dd 100644
--- a/Examples/base_entity/Program.cs
+++ b/Examples/base_entity/Program.cs
@@ -97,6 +97,8 @@ namespace base_entity
             BaseEntity.Initialization(fsql, () => _asyncUow.Value);
             #endregion
 
+            var sql = fsql.CodeFirst.GetComparisonDDLStatements(typeof(EMSServerModel.Model.User), "testxsx001");
+
             var test01 = EMSServerModel.Model.User.Select.IncludeMany(a => a.Roles).ToList();
             var test02 = EMSServerModel.Model.UserRole.Select.ToList();
             var test01tb = EMSServerModel.Model.User.Orm.CodeFirst.GetTableByEntity(typeof(EMSServerModel.Model.User));
diff --git a/Examples/base_entity/Test01/User.cs b/Examples/base_entity/Test01/User.cs
index be4fbeb2..e790301c 100644
--- a/Examples/base_entity/Test01/User.cs
+++ b/Examples/base_entity/Test01/User.cs
@@ -94,10 +94,13 @@ namespace EMSServerModel.Model
 		/// <summary>
 		/// 职务编号
 		/// </summary>
-		[JsonProperty]
-		public long? TitleId { get; set; }
+		[JsonProperty, Column(IsNullable = true)]
+		public long TitleId { get; set; }
+
+		[JsonProperty]
+		public long TitleId2 { get; set; }
+
 
-		
 		///// <summary>
 		///// 创建时间
 		///// </summary>
diff --git a/FreeSql.Tests/FreeSql.Tests/MsAccess/MsAccessCodeFirstTest.cs b/FreeSql.Tests/FreeSql.Tests/MsAccess/MsAccessCodeFirstTest.cs
index 622c63d3..5a6a3941 100644
--- a/FreeSql.Tests/FreeSql.Tests/MsAccess/MsAccessCodeFirstTest.cs
+++ b/FreeSql.Tests/FreeSql.Tests/MsAccess/MsAccessCodeFirstTest.cs
@@ -245,7 +245,7 @@ namespace FreeSql.Tests.MsAccess
             var itemstb = select.ToDataTable();
         }
 
-        [Table(Name = "tb_alltype")]
+        [Table(Name = "tb_alltype_insert")]
         class TableAllType
         {
             [Column(IsIdentity = true, IsPrimary = true)]
diff --git a/FreeSql/Internal/UtilsExpressionTree.cs b/FreeSql/Internal/UtilsExpressionTree.cs
index e9f4d453..a499e1ff 100644
--- a/FreeSql/Internal/UtilsExpressionTree.cs
+++ b/FreeSql/Internal/UtilsExpressionTree.cs
@@ -101,6 +101,8 @@ namespace FreeSql.Internal
                     continue;
                 }
                 if (tp == null && colattr != null) colattr.IsIgnore = true; //无法匹配的属性，认定是导航属性，且自动过滤
+                var colattrIsNullable = colattr?._IsNullable;
+                var colattrIsNull = colattr == null;
                 if (colattr == null)
                     colattr = new ColumnAttribute
                     {
@@ -119,6 +121,8 @@ namespace FreeSql.Internal
                 else
                     colattr.DbType = colattr.DbType.ToUpper();
 
+                if (colattrIsNull == false && colattrIsNullable == true) colattr.DbType = colattr.DbType.Replace("NOT NULL", "");
+                if (colattrIsNull == false && colattrIsNullable == false) colattr.DbType = Regex.Replace(colattr.DbType, @"\bNULL\b", "").Trim() + " NOT NULL";
                 if (colattr._IsNullable == null && tp != null && tp.isnullable == null) colattr.IsNullable = tp.dbtypeFull.Contains("NOT NULL") == false;
                 if (colattr.DbType?.Contains("NOT NULL") == true) colattr.IsNullable = false;
                 if (string.IsNullOrEmpty(colattr.Name)) colattr.Name = p.Name;