Linq Join 方式

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// linq 正規 Join 方式 DataTable dt = (from l in db.Log join u in db.User on l.InsertUserId equals u.Id into lu from j1 in lu.DefaultIfEmpty() join i in db.Item on l.ItemId equals i.Id into li from j2 in li.DefaultIfEmpty() join it in db.ItemType on j2.ItemTypeId equals it.Id select new { Id = l.Id, 日期 = l.Date, 項目 = it.ItemTypeName + "-" + j2.ItemName, 價格 = l.Price, 人員 = j1.UserName, } ).ToDataTable(); // linq 非正規 Join 方式 DataTable dt = ( from l in db.Log from u in db.User from i in db.Item from it in db.ItemType where 1 == 1 && l.InsertUserId == u.Id && l.ItemId == i.Id && i.ItemTypeId == it.Id && (i.ItemName.Contains(Query) || it.ItemTypeName.Contains(Query)) select new { Id = l.Id, 日期 = l.Date, 項目 = it.ItemTypeName + "-" + i.ItemName, 價格 = l.Price, 人員 = u.UserName, } ).ToDataTable();