从innumerable循环中选择某个列值 [英] selecting a certain column value from looping in ienumerable

问题描述

我从存储过程中得到了IEnumerable的结果，并且正在遍历结果以获取column(GUID)的值.我不确定如何继续从foreach循环的结果集中获取Guid列

I have a result of IEnumerable from a stored procedure and i am looping through the results inorder to get the value of a column(GUID). I am unsure of how to go about on getting the Guid column from my results set in the foreach loop

这就是我所拥有的:

var results = GetGuids(instId);
foreach (var item in results)
{

}

public IEnumerable GetGuids(int id)
        {
            using (SqlCommand _command = new SqlCommand("StoredProc"))
            {
                _command.Connection = new SqlConnection(conString);
                _command.Connection.Open();
                _command.CommandType = CommandType.StoredProcedure;
                _command.Parameters.AddWithValue("@ItemID", id);

                return _command.ExecuteReader();
            }
        }

推荐答案

您不能直接在非通用IEnumerable上直接使用大多数常规linq扩展方法...但是您可以调用

You can't use most of the normal linq extension methods directly on the non-generic IEnumerable... but you can call .Cast<T>() to make it an IEnumerable<T>. At that point, things get easier:

public IEnumerable<Guid> GetGuids(int id)
{
    using (SqlCommand _command = new SqlCommand("StoredProc"))
    {
        _command.Connection = new SqlConnection(conString);
        _command.Connection.Open();
        _command.CommandType = CommandType.StoredProcedure;
        _command.Parameters.Add("@ItemID", SqlDbType.Int).Value =  id;

            return _command.ExecuteReader()
                  .Cast<DbDataRecord>()
                  .Select(r => (Guid)r["GuidColumn"]);
    }
} 

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