请问有人可以帮忙吗?我需要在 Extn_In_Call_Records = Extn_Number 上返回一个表,如果任一侧不匹配,仍然返回一个计算,就像 SQL 完全外连接一样。我花了几个小时看这个,但无法让它工作!如果删除联合,我可以让代码在下面工作,但它只返回匹配的结果。数据表是从 MYSQL 填充的。任何帮助都会很棒。
//Full Table
DataTable fullext = new DataTable();
fullext.Columns.Add("Extn_In_Call_Records", typeof(string));
fullext.Columns.Add("Total_Calls", typeof(int));
fullext.Columns.Add("Extn_Number", typeof(string));
fullext.Columns.Add("Phys_Switch_Name", typeof(string));
//End Full Table
try
{
//Full Result
var result = from callrc in callrecdt.AsEnumerable()
join physex in physextns.AsEnumerable()
on callrc["Extn_In_Call_Records"] equals physex["Extn_Number"]
.Union
from physex in physextns.AsEnumerable()
join callrc in callrecdt.AsEnumerable()
on physex["Extn_Number"] equals callrc["Extn_In_Call_Records"]
select fullext.LoadDataRow(new object[] {
callrc["Extn_In_Call_Records"],
callrc["Total_Calls"],
physex["Extn_Number"] == null ? "" : physex["Extn_Number"],
physex["Phys_Switch_Name"] == null ? "" : physex["Phys_Switch_Name"]
}, false);
result.CopyToDataTable();
fullresult.DataSource = fullext;
结果可见
Extn_In_Call_Records Total_Calls Extn_Number Phys_Switch_Name
null 20 0 Hospital
null 310 1 Hospital
4 132 4 Hospital
2004 null null Hospital
2006 2 2006 Hospital
Per LINQ - 完全外连接 https://stackoverflow.com/questions/5489987/linq-full-outer-join,执行完整外连接的最简单方法是合并两个左连接。 LINQ 中的左连接(使用扩展方法语法)采用以下形式:
var leftJoined = from left in lefts
join right in rights
on left.Key equals right.Key
into temp
from newRight in temp.DefaultIfEmpty(/* default value for right */)
select new
{
/* use left and newRight to construct the joined object */
}
就您而言,您想要执行以下操作:
// initialize some default elements to use later if
// they're of the same type then a single default is fine
var defaultPhysex = new {...};
var defaultCallrc = new {...};
var left = from callrc in callrecdt.AsEnumerable()
join physex in physextns.AsEnumerable()
on callrc["Extn_In_Call_Records"] equals physx["Extn_Number"]
into temp
from physex in temp.DefaultIfEmpty(defaultPhysex)
select new
{
// callrc is accessible here, as is the new physex
Field1 = ...,
Field2 = ...,
}
var right = from physex in physextns.AsEnumerable()
join callrc in callrecdt.AsEnumerable()
on callrc["Extn_In_Call_Records"] equals physx["Extn_Number"]
into temp
from callrc in temp.DefaultIfEmpty(defaultCallrc)
select new
{
// physex is accessible here, as is the new callrc
Field1 = ...,
Field2 = ...,
}
var union = left.Union(right);
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