如何：串联两个序列 (LINQ to SQL)
使用 Concat<TSource> 运算符可串联两个序列。
Concat<TSource> 运算符是为有序多重集定义的，其中接收方的顺序与参数的顺序相同。
在 SQL 中排序是产生结果前的最后一步。 因此，Concat<TSource> 运算符是通过使用 UNION ALL 实现的，并且不保留其参数的顺序。 为确保结果中的顺序正确，一定要显式地对结果进行排序。
示例
此示例使用 Concat<TSource> 返回由所有 Customer 和 Employee 的电话和传真号码组成的序列。
Dim custQuery = _
(From c In db.Customers _
Select c.Phone) _
.Concat _
(From c In db.Customers _
Select c.Fax) _
.Concat _
(From e In db.Employees _
Select e.HomePhone)
For Each custData In custQuery
Console.WriteLine(custData)
Next
IQueryable<String> custQuery =
(from cust in db.Customers
select cust.Phone)
.Concat
(from cust in db.Customers
select cust.Fax)
.Concat
(from emp in db.Employees
select emp.HomePhone)
;
foreach (var custData in custQuery)
{
Console.WriteLine(custData);
}
此示例使用 Concat<TSource> 返回由所有 Customer 和 Employee 的名字和电话号码映射组成的序列。
Dim infoQuery = _
(From cust In db.Customers _
Select Name = cust.CompanyName, Phone = cust.Phone) _
.Concat _
(From emp In db.Employees _
Select Name = emp.FirstName & " " & emp.LastName, _
Phone = emp.HomePhone)
For Each infoData In infoQuery
Console.WriteLine("Name = " & infoData.Name & _
", Phone = " & infoData.Phone)
Next
var infoQuery =
(from cust in db.Customers
select new { Name = cust.CompanyName, cust.Phone }
)
.Concat
(from emp in db.Employees
select new
{
Name = emp.FirstName + " " + emp.LastName,
Phone = emp.HomePhone
}
);
foreach (var infoData in infoQuery)
{
Console.WriteLine("Name = {0}, Phone = {1}",
infoData.Name, infoData.Phone);
}