如何在LinqPad中执行左连接

Question

如何让 LinqPad 执行下面所示的左连接？

var query = 
            from s in db.CDBLogsHeaders
                    .OrderByDescending(g => g.LogDateTime)
                    from sc in db.StyleColors
                        .Where(stylecolor => stylecolor.id == (int?)s.StyleColorID)
                        .DefaultIfEmpty()
                    from c in db.StyleHeaders
                        .Where(styleHeader => styleHeader.id == (int?)s.StyleHeaderID)
                        .DefaultIfEmpty()
        select new 
        {
            CDBLogsHeaderId = s.Id,
            Merchandiser = c.Merchandiser,
            Material = s.Material,
            Season = s.Season,
            LogsHeaderLogType = s.LogType,
            PushFromTo = s.PushFromTo,
            LinePlan = s.LinePlan,
            QuikRefNumber = s.QuikRefNumber,
            PLMOrigin = s.PLM_Origin,
            SeasonOriginal = c.SeasonOriginal,
            SeasonCurrent = c.SeasonCurrent,
            StyleHeaderId = c.Id,
            StyleCode = c.StyleCode,
            StyleColorsColorCode = sc.ColorCode
        };

    query.Dump();

在 Management Studio 中，Linq Pad 创建的 SQL 运行得非常完美，但 Linq Pad 却没有显示任何行，并出现以下错误：

“InvalidOperationException: The null value cannot be assigned to a member with type System.Int32 which is a non-nullable value type.”

我该如何让 Linq Pad 正常工作以便我可以使用它？

- monkeyjumps

---

http://meta.stackexchange.com/a/128558/102937 - Robert Harvey

Answer 1

在您的匿名类型中，请确保您的整数返回整数。

更改为：

StyleHeaderId = c.Id,

To

StyleHeaderId = (c.Id == null ? 0 : c.Id),

- batman 74