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我如何获得一个独特的,下令从DataTable使用LINQ的名单吗?

Let's say I have a DataTable with a Name column. I want to have a collection of the unique names ordered alphabetically. The following query ignores the order by clause.

var names =
    (from DataRow dr in dataTable.Rows
    orderby (string)dr["Name"]
    select (string)dr["Name"]).Distinct();

Why does the orderby not get enforced?

2016年12月05日42分27秒

To make it more readable and maintainable, you can also split it up into multiple LINQ statements.

  1. First, select your data into a new list, let's call it x1, do a projection if desired
  2. Next, create a distinct list, from x1 into x2, using whatever distinction you require
  3. Finally, create an ordered list, from x2 into x3, sorting by whatever you desire

2016年12月05日42分27秒

The problem is that the Distinct operator does not grant that it will maintain the original order of values.

So your query will need to work like this

var names = (from DataRow dr in dataTable.Rows
             select (string)dr["Name"]).Distinct().OrderBy( name => name );

2016年12月05日42分27秒

var sortedTable = (from results in resultTable.AsEnumerable()
select (string)results[attributeList]).Distinct().OrderBy(name => name);

2016年12月05日42分27秒

Try out the following:

dataTable.Rows.Cast<DataRow>().select(dr => dr["Name"].ToString()).Distinct().OrderBy(name => name);

2016年12月05日42分27秒

Try the following

var names = (from dr in dataTable.Rows
             select (string)dr["Name"]).Distinct().OrderBy(name => name);

this should work for what you need.

2016年12月05日42分27秒