Left Outer Join on two Datatables in C#.net

Question

Working on C#

I have two DataTables with one common column.

I want to perform a Left outer join on these two and store the result in a third datatable.

 

Datatable1 contains columns                                                    ColA ColB ColC

Datatable2 contains columns                                                    Col1 ColA Col2 Col3 Col4 Col5 Col6

 

Datatable3 will contain                                                              Col A ColB Col 1 Col2   [ColA is common)

 

 

 

How can I do that?

An example code would be of great help.

 

Thanks..

 

Answer 1

Pls help

Answer 2

You could use LINQ to create joined result. Here are some samples how to use LINQ with DataTables

 

http://msdn.microsoft.com/en-us/vbasic/bb738025.aspx

 

If you cannot use LINQ, you would need to create helper class similar to the following sample

 

http://support.microsoft.com/kb/326080/en-us

 

Answer 3

I would simply query the database again and populate that DataTable. I like to keep solutions simple. Querying a DataTable is easy enough, but joined tables I haven't found to be easy, if someone has an example I would like to see it.

 

The example the other gentleman left seems easy enough in LINQ, but I am still on .NET 2.0

 

So i would just do a left outer join and populate a DataTable, and then query that DataTable again the next time.

 

Answer 4

Hi you can check with following Linq query

var result = from x in dtA.AsEnumerable()
                         join y in dtB.AsEnumerable() on x.Field<string>("AppStatusName").ToUpper() equals y.Field<string>("Application_Stage_fat").ToUpper()
                         into xy
                         from y in xy.DefaultIfEmpty()
                         select new { appstate = x.Field<string>("AppStatusName"), FAT = (y == null) ? null : y.Field<int?>("StatusCount")};

hope this will work

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Hasibul Haque,MCC,MCPD hasibulhaque.com

Answer 5

Just as an FYI Hasibul, check the date when this question was asked. --> Friday, June 20, 2008 6:39 AM

We probably shouldn't be resurrecting dead threads just to show our astuteness.