C# how to read two excel sheets using join

Posted on 2013-06-21
Medium Priority
Last Modified: 2013-08-25
I have figured out how to read in a spreadsheet in c# using odbcDataReader. See below:

                string SQL = "Select * from [TransactionHeader$]";
                "select * from [TransactionMaster$]";
                using (OdbcCommand com = new OdbcCommand(SQL, con1, null))
                    using (OdbcDataReader reader = com.ExecuteReader())
                        while (reader.Read())
                            int Fields = reader.FieldCount;
                            string value = reader[0] + " " + reader[1] + " ";

                            MessageBox.Show(value.ToString() + Fields);

Now I would like to be able to do a similiar type of read, but joining two Sheets (TransascionMaster & TransactionHeader). The SQL statement would be something like this:

select * from [TransactionMaster$], [TransactionHeader$] where TransactionMaster.CELL1 = TransactionHeader.CELL5"

Can I do this and if so what is the format of the SQL statement?

Question by:pclarke7
  • 2
LVL 22

Expert Comment

ID: 39267131
I don't think this is possible without spending more time rebuilding all the parts.  I've never tried this with an ODBC connection, but since each sheet is a separate object, the only way I can see to do this is to either pull each object separately then merge them in C# or to get Excel to merge the parts (which would be rather slow) then use C# to to what you wanted.

Since they are two separate objects, imagine that you are working with two separate forms and you want to merge the contents.  Ultimately you need to either go to each form to get the contents or you need to get the forms to merge themselves into a new object then get the contents.
LVL 17

Accepted Solution

andrewssd3 earned 1500 total points
ID: 39267133
You should be able to do this using a sql statement like
select * from 
	[TransactionMaster$] AS m
	INNER JOIN [TransactionHeader$] AS h ON m.CELL1 = h.CELL5

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Assuming that CELL1 and CELL5 are column headers on the 2 sheets

Author Comment

ID: 39267857
Thanks for both comments.
Andrew I went with your suggestion and below is the SQL statement:

string SQL = "Select * from [TransactionMaster$] AS m LEFT JOIN [TransactionHeader$] AS h ON m.T2_TransactionID=h.T1_TransID and m.T2_CompanyID= " + "'" + CompanyAlpha + "'" + " and m.T2_CompanyID=" + "'" + globals.MyTrans.Transaction + "'"  + " Order by m.T2_SeqNo";

However I get the following error

ERROR [HY000¿] [Microsoft][ODBC Excel Driver] JOIN expression not supported.

any ideas ?

LVL 17

Expert Comment

ID: 39267977
I'm pretty sure I have used joins across sheets with the Excel ODBC driver in the past from VBA, but it's obviously not implemented in yours. I'm not very experienced with .NET data objects, but isn't it possible to created Datasets separately and join them with a DataRelation? This is an example of doing this, but you'd need to ask more of a .Net expert whether this is feasible and/or sensible in your situation.

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