How to select number from Excel file?

Question

I use this code to load an Excel file into a datatable:

 public static DataTable ImportExcelFile(string connectionString)
        {
            DbProviderFactory factory =
                DbProviderFactories.GetFactory("System.Data.OleDb");
            var listCustomers = new DataTable();

            using (DbConnection connection = factory.CreateConnection())
            {
                if (connection != null)
                {
                    connection.ConnectionString = connectionString;
                    using (DbCommand command = connection.CreateCommand())
                    {
                        // Cities$ comes from the name of the worksheet
                        command.CommandText = "SELECT * FROM [Sheet1_2$]";
                        connection.Open();
                        using (DbDataReader dr = command.ExecuteReader())
                        {
                            listCustomers.Load(dr);
                        }
                    }
                }
            }
            return listCustomers;
        }

The problem is, some columns in the Excel file, for example, AccountID, contains both string data ('quanmv') and number (123456). When I use this code, it just ignores cell with number value, and leave it with blank.

How can I fix that?

Thank you so much.

Answer 1

By default, the connection to excel tries to guess data types of columns. If it guesses wrong, it may leave nulls where types don't convert. You can add IMEX=1 to the connection string to turn off this automatic guessing, and treat all values as strings.