c# - 消除 LET 运算符和 SqlFunctions

Question

请考虑这个查询:

from r in ent.MyTable
group r by new { r.EmployeeName, r.EmployeeID } into g
let c = " (" + SqlFunctions.StringConvert((decimal?)g.Count()) + " )"
select new
{
    EmployeeName = g.Key.EmployeeName + c ,
    EmployeeID = g.Key.EmployeeID
});

效果很好。当我想改用此查询时，出现错误:

from r in ent.MyTable
group r by new { r.EmployeeName, r.EmployeeID } into g
select new
{
    EmployeeName = g.Key.EmployeeName + " (" + g.Count() + ")",
    EmployeeID = g.Key.EmployeeID
});

错误:

Can not convert System.Object to System.String

我该怎么做？

Answer 1

为什么不对输出进行双重转换？

from r in ent.MyTable
group r by new { r.EmployeeName, r.EmployeeID } into g
select new
{
    EmployeeName = g.Key.EmployeeName,
    Count = g.Count(),
    EmployeeID = g.Key.EmployeeID
}
into tmp
select new
{
    EmployeeName = tmp.EmployeeName + "(" + Count + ")",
    EmployeeID = tmp.EmployeeID
}