Update bluecopy

Src/Asp.Net/SqlServerTest/UnitTest/Updateable.cs

@@ -93,8 +93,19 @@ namespace OrmTest
             Db.Updateable<Order>()
              .SetColumns(it => new Order { Name = "a", CreateTime = DateTime.Now })
              .SetColumns(it => new Order() { Price = 1 }).Where(it => it.Id == 1).ExecuteCommand();
+
+            Db.CodeFirst.InitTables<Unitbluecopy>();
+            Db.Insertable(new Unitbluecopy()).UseSqlServer().ExecuteBlueCopy();
         }
     }
+
+    public class Unitbluecopy
+    {
+        public int Id { get; set; }
+        [SugarColumn(IsNullable =true)]
+        public decimal? x { get; set; }
+    }
+
     public class NullTest
     {
         public int id { get; set; }

Src/Asp.Net/SqlSugar/Realization/SqlServer/SqlBuilder/SqlServerBlueCopy.cs

@@ -81,6 +81,10 @@ namespace SqlSugar
                                 value.Value = Convert.ToDateTime("1753/01/01");
                             }
                         }
+                        if (value.Value == null)
+                        {
+                            value.Value = DBNull.Value;
+                        }
                         dr[item.ColumnName] = value.Value;
                     }
                 }