遍历从var返回的数据以获取列的名称和值

匿名类型是局部作用域的。你不能在定义它们的方法之外使用它们(除了诉诸于 horrible grotty hack ).为什么不定义一些以强类型方式表示数据的域类呢:

public class Table
{
    public string Column1 { get; set; }
    public string Column2 { get; set; }
}

public static IEnumerable<Table> GetDataSource(string QueryName)
{
    MyEntity myEntity = new MyEntity();
    switch (QueryName)
    {
        case "FirstQuery":
            return from x in myEntity.TableName
                   select new Table
                   {
                       Column1 = x.FirstColumn,
                       Column2 = x.SecondColumn
                   };
    }
    return Enumerable.Empty<Table>();
}

public class Table{
public string Column1 { get; set; }
public int Column2 { get; set; }}

 public static IEnumerable<T> GetDataSource<T>()
    {
        MyEntity myEntity = new MyEntity();

        if (typeof(T) == typeof(Table))
        {
            IQueryable<Table> query = from x in myEntity.Table1
                   select new Table
                   {
                       Column1 = x.TheColumn1,
                       Column2 = x.TheColumn2
                   };

           return query.ToList().Cast<T>();
        }
        if (typeof(T) == typeof(Table2))
        {
            IQueryable<Table2> query = from x in myEntity.Table2
                   select new Table2
                   {
                       TestColumn1 = x.TheColumn123,
                       TestColumn2 = x.TheColumn321
                   };

            return query.ToList().Cast<T>();
        }

        return Enumerable.Empty<T>();
    }