Upload CSV file to SQL server

Question

What is the best way to upload a large csv data file into SQL server using C# ? The file contains about 30,000 rows and 25 columns.

Answer 1

    private void GetDataTabletFromCSVFile(string fileName)
    {
        DataTable dt = new DataTable();
        //dt.TableName = fileName;

        try
        {
            using (TextFieldParser csvReader = new TextFieldParser(fileName))
            {
                csvReader.SetDelimiters(new string[] { "," });
                csvReader.HasFieldsEnclosedInQuotes = true;
                string[] colFields = csvReader.ReadFields();
                //foreach (string column in colFields)
                //{
                //    DataColumn datecolumn = new DataColumn(column);
                //    datecolumn.AllowDBNull = true;
                //    dt.Columns.Add(datecolumn);
                //}
                dt.Columns.AddRange(new DataColumn[8] {
                    new DataColumn("Symbol", typeof(string)),
                new DataColumn("ISIN", typeof(string)),
                new DataColumn("Company", typeof(string)),
                new DataColumn("FirstListingDate", typeof(string)),
                new DataColumn("FaceValue", typeof(string)),
                new DataColumn("PaidUpValue", typeof(string)),
                new DataColumn("MarketLot",typeof(string)),
                new DataColumn("industry",typeof(string))
                });
                while (!csvReader.EndOfData)
                {
                    string[] fieldData = csvReader.ReadFields();
                    //Making empty value as null
                    for (int i = 0; i < fieldData.Length; i++)
                    {
                        if (fieldData[i] == "")
                        {
                            fieldData[i] = null;
                        }
                    }
                    dt.Rows.Add(fieldData);
                }
                var builder = new ConfigurationBuilder()
                    .SetBasePath(Path.GetDirectoryName(System.Reflection.Assembly.GetExecutingAssembly().Location))
                    .AddJsonFile("appsettings.json");

                var configuration = builder.Build();
                string DBconnection = configuration.GetSection("ConnectionString").Value;
                using (SqlConnection dbConnection = new SqlConnection(DBconnection))
                {
                    dbConnection.Open();
                    using (SqlBulkCopy s = new SqlBulkCopy(dbConnection))
                    {
                        s.DestinationTableName = "Static.dbo.Securitiesinfo";
                        foreach (var column in dt.Columns)
                            s.ColumnMappings.Add(column.ToString(), column.ToString());
                        s.WriteToServer(dt);
                    }
                }

            }
        }
        catch (Exception ex)
        {
            var x = ex;
        }

    }

Answer 2

Use System.Data.SqlClient.SqlBulkCopy class to insert data into Sql tables. To use that class you also need to convert CVS data to DataTable, see here one of the ways.