LINQ to SQL C#COALESCE

Question

鉴于下表:

Length | Width | Color | ID
===========================
    18 |    18 |  blue |  1
---------------------------
    12 |    12 |   red |  1
---------------------------

我想生成一个列/行:

 SIZES
 =================
 18 x 18, 12 x 12,

我可以在SQL中执行以下操作:

DECLARE @SIZES VARCHAR(8000)
SELECT @SIZES = COALESCE(@SIZES, '') + Convert(varchar(80), [Length]) + ' x ' + 
                Convert(varchar(80), [Width]) + ', '
FROM table
where ID = 1
GROUP BY [Length], [Width]
ORDER BY [Length], [Width]
SELECT SIZES = @SIZES

但我无法弄清楚如何在LINQ中做到这一点.

我得到的最接近的是:

from t in table
where id == 1
group t by new {
                 t.Length,
                 t.Width
               } into g
orderby g.Key.Length, g.Key.Width
select new {
             SIZES = (Convert.ToInt32(g.Key.Length) + " x " +
                      Convert.ToInt32(g.Key.Width) + ", ")
           }

这会产生一列和两行:

SIZES
========
18 x 18,
12 X 12,

皈依者对这个问题并不重要.虽然列都是整数,但列被定义为浮点数.关键是COALESCE函数我无法弄清楚如何在LINQ中做到这一点.

Answer 1

尝试??(null coalesce operator),如:

t.Length ?? 0