Question

我有这个问题：

    var ftr_dist = db.DIST_VIEW.Where(x => x.CITY == "Los Angeles");
    var mst2 = db.TB_SERVICE.Where(x => x.ID == x.ID);
    var trf2 = db.TYPE.Where(x => x.ID == x.ID);

    var Data = (from ftr in ftr_dist
                      join mst in mst2 on ftr.CUSTOMER_ID equals mst.CUSTOMER_ID
                      join trf in trf2 on mst.TYPE_ID equals trf.ID
                      select new TypeObj { City = ftr.CITY, County = ftr.COUNTY, Type = trf.Type }
                      ).OrderBy(i => i.City).ThenBy(i => i.County).ToList();

ftr_dist有大约72000行。 mst2有1100000行，trf2有340行。但是获取数据需要很长时间。如何更快地进行此查询？感谢。

Answer 1

您实际上是在执行4种不同的查询。查询确实需要比sql字符串更长的查询...尝试使用Linq。将所有查询合并为一个。

我对你的lambda查询（x =＆gt; x.ID == x.ID）有点困惑。您可能需要将其添加到下面的

var data = from ftr in db.DIST_VIEW
           join mst in db.TB_SERVICE on ftr.CUSTOMER_ID equals 
           mst.CUSTOMER_ID
           join trf in db.TYPE on trf.TYPE_ID equals ftr.ID
           where ftr.CITY == "Los Angeles"
           select new TypeObj 
           {
            City = ftr.City,
            Country = ftr.County,
            Type - trf.Type
           }.OrderBy(i => i.City).ThenBy(i => i.County).ToList();

LINQ double Join执行时间太长

1 个答案: