Add support for inventory timestamps

PartSource.Data/Models/PartAvailability.cs

@@ -0,0 +1,21 @@
+using System;
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+
+namespace PartSource.Data.Models
+{
+    public class PartAvailability
+    {
+        [Column(Order = 0)]
+        [DatabaseGenerated(DatabaseGeneratedOption.None)]
+        public int Store { get; set; }
+
+        [Column(Order = 1)]
+        [DatabaseGenerated(DatabaseGeneratedOption.None)]
+        public int SKU { get; set; }
+
+        public int? QTY { get; set; }
+
+        public DateTime? Updated { get; set; }
+    }
+}