- add isKey property

GBase/Attributes/GBaseColumnAttribute.cs

@@ -13,6 +13,11 @@ namespace GBase.Attributes
     [AttributeUsage(AttributeTargets.Property)]
     public class GBaseColumnAttribute : Attribute
     {
+        public GBaseColumnAttribute(bool isKey = false)
+        {
+            IsKey = isKey;
+        }
         
+        public bool IsKey { get; }
     }
 }