solve error "undefined function convert in expression"

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C#2.0

C#

Hi developers,
I have a csv file that is loaded in datagridview by using dataset.
The problem is:
I want to change dates format in dataset not in datagridview before loading a csv file in datagridview

public static DataSet GetDataset(string filename)
       {

               string Connectionstring = string.Format("Provider=Microsoft.Jet.OLEDB.4.0;Data Source={0};Extended Properties=Text;",
                   Path.GetDirectoryName(filename));
               string cmdString = string.Format("SELECT *FROM {0}", Path.GetFileName(filename));
               string cmdstring = string.Format(@" select convert(varchar, getdate(), 103)  From {0}", Path.GetFileName(filename));


               DataSet dataset = new DataSet();
               using (OleDbConnection olconn = new OleDbConnection(Connectionstring))
               {
                   olconn.Open();
                   OleDbDataAdapter adapter = new OleDbDataAdapter();
                   adapter.SelectCommand = new OleDbCommand(cmdString, olconn);
                   adapter.SelectCommand = new OleDbCommand(cmdstring, olconn);
                   adapter.Fill(dataset, "Test");
                   olconn.Close();
               }
               return dataset;
           }

but when I write a code like this

string cmdstring = string.Format(@" select convert(varchar, getdate(), 103)  From {0}, Path.GetFileName(filename));

Error is
undefined function convert in Expression

A main problem is that dateformat change in multiple columns
not single or more dates are split into multiple rows and columns
so I do not know how more columns are changed.
I want to change all of the columns rows dates in dataset, by using this sql query.
please solve my problem and Correct this code