神祖牌位管理模組，掛單模組前端URL添加HTTP_HOST

web/App_Code/api/AncestralTabletStatisticsController.cs

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+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Web;
+using System.Web.Http;
+
+/// <summary>
+/// AncestralTabletStatisticsController 的摘要描述
+/// </summary>
+public class AncestralTabletStatisticsController:ApiController
+{
+    private Model.ezEntities db = new Model.ezEntities();
+    [HttpGet]
+    [Route("api/ancestraltablet/statistics/positions/availablepositions")]
+    public IHttpActionResult GetAvailablePositions()
+    {
+        var query =
+            from a in db.AncestralTabletArea // 区域表
+            join p in db.AncestralTabletPosition
+                on a.AreaId equals p.AreaId into ap
+            from p in ap.DefaultIfEmpty()
+            join r in db.AncestralTabletRegistrant
+                on p.PositionId equals r.PositionId into pr
+            from r in pr.DefaultIfEmpty()
+            group new { a, p, r } by new { a.AreaId, a.AreaName } into g
+            select new
+            {
+                AreaId = g.Key.AreaId,
+                AreaName = g.Key.AreaName,
+                TotalPositions = g.Count(x => x.p != null),                   // 总位置数
+                AvailableCount = g.Count(x => x.p != null && x.r == null)     // 可用位置数（未登记）
+            };
+
+        var result = query.ToList();
+        return Ok(result);
+    }
+
+}