Validation of Excel file data before importing to Database

Question

I'm trying to read data from an Excel file to a DataTable . I know that we can assign different DataTypes for a DataColumn when adding columns to a DataTable . So far I have tried the following,

DataTable dt = new DataTable();
dt.Columns.AddRange(new DataColumn[2]
{
    new Datacolumn("column1", typeof(string)),
    new DataColumn("column2", typeof(int))
});

And my excel file has data in two columns as follows,

column1------column2

abc----------------230

def----------------230tr

As you can see above, the second row second column has a value of '230tr' which the DataTable should not accept an throw an exception with the invalid data field and row number.

Praveena.

Answer 1

In your code, where you are reading the excel values to insert, you should employ the C# function: [Int32.TryParse][1] or float.Try​Parse ;

which will tell you whether the string will convert to a float (or integer) in which case don't insert it.

You can see a detailed example/answer here :

Answer 2

you can try in that way.

      DataTable dt = new DataTable();
        dt.Columns.AddRange(new DataColumn[2]
        {
          new DataColumn("column1", typeof(int)),
          new DataColumn("column2", typeof(string))
        });

        dt.Clear();
        try
        {
            string input = string.Empty;
            input = Console.ReadLine();
            if (Regex.IsMatch(input, @"^[a-zA-Z]+$"))
            {
                dt.Rows.Add(1, input);
            }
            Console.WriteLine(dt.Rows[0]["column2"]);
            Console.ReadKey();
        }
        catch(Exception ex)
        {
            Console.WriteLine(ex);
            Console.ReadKey();
        }

Answer 3

Thank you everyone for their response and I found an easy solution for my question while working with DataTables . My main task was to read data rows from an Excel file sheet and validate each row data before adding it to my database table(using OracleBulkCopy) and notify the user with any invalid data fields in the Excel file sheet.

While I was importing data into the DataTable from the Excel file sheet using oda.Fill(dt); I realized that some of the DataRow fields are empty(null) during the process of data addition to DataTable .

As I have mentioned above in the main question we can assign the DataType for a DataColumn in a DataTable as follows,

DataTable dt = new DataTable();
dt.Columns.AddRange(new DataColumn[3]
{
    new Datacolumn("column1", typeof(string)),
    new DataColumn("column2", typeof(double)),
    new DataColumn("column3", typeof(DateTime))
});

And my Excel file sheet would be as follows,

column1-----------------column2----------------------column3

abcd----------------------20000-------------------------20-Dec-2018

efgh-----------------------56500.5---------------------- xyz17-Mar-2018

ijklm-----------------------67000------------------------1-Jan-2018

In the above table 3rd row 3rd column RowData is in invalid date type (xyz17-Mar-2018). While performing oda.Fill(dt); for the above table, this data field gets added as a null RowData to the DataTable . It would be the same for other columns if the importing data fields are not in the type of defined DataColumn type. So My final step was to check each row data of DataTable which has a null field and throw the user with an error message mentioning the row number and column name.

int errorRowNumber = 0;

private bool validateDataTableData(DataTable dt, string dtColumnName)
{
    Boolean isTrue = false;

    foreach (DataRow r in dt.Rows)
    {
          if(!string.IsNullOrEmpty(r[dtColumnName].ToString()))
          {
                isTrue = false;
                errorRowNumber = dt.Rows.IndexOf(r) + 2;
                break;
          }
    }
    return isTrue;
}