为所有数据库表增加TableBase基类，所有表增加Id和CreateDateTime字段

CalendarNotepad/Models/PlusFileUnit.cs

@@ -3,7 +3,7 @@
     /// <summary>
     /// 附件文件单元
     /// </summary>
-    public class PlusFileUnit
+    public class PlusFileUnit:TableBase
     {
         /// <summary>
         /// 文件指纹ID

CalendarNotepad/Models/TableBase.cs

@@ -0,0 +1,20 @@
+using System.ComponentModel.DataAnnotations;
+
+namespace CalendarNotepad.Models
+{
+    /// <summary>
+    /// 数据表基类
+    /// </summary>
+    public abstract class TableBase
+    {
+        /// <summary>
+        /// 数据主键
+        /// </summary>
+        [Key]
+        public string Id { get; set; } = Guid.NewGuid().ToString();
+        /// <summary>
+        /// 记录创建或最后修改时间
+        /// </summary>
+        public DateTime CreateDateTime { get; set; } = DateTime.Now;
+    }
+}

CalendarNotepad/Models/WorkUnit.cs

@@ -7,7 +7,7 @@ namespace CalendarNotepad.Models
     /// 工作记录单元
     /// </summary>
     [Table("WorkUnit")]
-    public class WorkUnit
+    public class WorkUnit:TableBase
     {
         /// <summary>
         /// 工作日期

CalendarNotepad/Models/WorkUnitPlusFile.cs

@@ -3,7 +3,7 @@
     /// <summary>
     /// 工作单元附件对应关系
     /// </summary>
-    public class WorkUnitPlusFile
+    public class WorkUnitPlusFile:TableBase
     {
         /// <summary>
         /// 工作日期