kreta/Kreta.DataAccessManual/Extensions/DataSetExtensions.cs

using System;
using System.Collections.Generic;
using System.Data;
using System.Linq;

namespace Kreta.DataAccessManual.Extensions
{
    public static class DataSetExtensions
    {
        public static List<int> GetIdListFromFirstTable(this DataSet dataSet)
        {
            return dataSet.Tables[0]
                .AsEnumerable()
                .Select(r => r.Field<int>("ID"))
                .ToList();
        }

        public static DataTable ConvertColumnTypes(this DataTable dataTable, Dictionary<string, Type> columnNameColumnTypeDictionary)
        {
            var clonedDataTable = dataTable.Clone();
            foreach (var columnNameColumnType in columnNameColumnTypeDictionary)
            {
                clonedDataTable.Columns[columnNameColumnType.Key].DataType = columnNameColumnType.Value;
            }
            foreach (DataRow dataRow in dataTable.Rows)
            {
                clonedDataTable.ImportRow(dataRow);
            }

            return clonedDataTable;
        }

        public static DataTable ConvertColumnType(this DataTable dataTable, string columnName, Type newType)
        {
            return dataTable.ConvertColumnTypes(new Dictionary<string, Type> { { columnName, newType } });
        }
    }
}