Sort DataTable in C#

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Hello,
I return a cursor to a DataSet from Oracle. I would like to order the rows in the DataTable so I could rank them. However the order would be be the result of "column3" / "column4". I have tried the following with no luck.

DataTable crsDT = ds.Tables[0].Copy();
DataRow[] rows = new DataRow[crsDT.Rows.Count-1];
rows = crsDT.Select("column4 != 0","column3 / column4");

I know I can loop through the data and get my intended result, but I wanted to try something new to see if it would be more efficient.

Is this possible or should I go a different direction?

Posted 12-Nov-10 4:49am

badprog

Updated 12-Nov-10 4:55am

v2

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2 solutions

Solution 1

Could you not do something like this?

foreach( DataRow row in ds.Tables[0].Select("","column3 / column4") )
{
 int Rank = row.Item("column3") / row.Item("column4");

 // Do something with row and rank?
}

Posted 12-Nov-10 5:05am

MarqW

Comments

badprog 12-Nov-10 11:23am

MarqW,
System.IndexOutOfRangeException was unhandled by user code
Message="Cannot find column Column3 / Column4."
Source="System.Data"

Blew up in the ForEach definition.
Would my syntax be wrong? I know that the column names are correct, because I get the column names via
ds.Tables[0].Columns[3].ColumnName
ds.Tables[0].Columns[4].ColumnName

MarqW 12-Nov-10 11:24am

Hmm, try changing it to this:

ds.Tables[0].Select("","[column3] / [column4]") )

and maybe need brackets

ds.Tables[0].Select("","([column3] / [column4])") )

I'll be honest, I've not actually tried these :-)

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Henry Minute · Accepted Answer · 2010-11-12T05:14:00

Solution 2

How about adding a computed column to the DataTable and using that?

Posted 12-Nov-10 5:14am

Henry Minute

Comments

badprog 12-Nov-10 11:31am

Thanks Henry,
I am trying this now
Type tType = typeof(double);
DataColumn myCol = new DataColumn("RANK", tType, "Column3 / Column4");
crsDT.Columns.Add(myCol);
I just have to figure out what to do when Column4 is zero. Once I do, I think that will work.