SqlDataReader.Read和SqlDataReader.NextResult的区别 [英] Difference between SqlDataReader.Read and SqlDataReader.NextResult

问题描述

这是这两种方法的主要区别？在MSDN网站上它是象下面这样解释，但我不明白。

What is the main difference between these two methods? On the msdn website it is explained like below but I don't understand it.

读进展SqlDataReader的下一条记录。 （重写 DbDataReader.Read（）。）

Read Advances the SqlDataReader to the next record. (Overrides DbDataReader.Read().)

NextResult ，使数据读取到下一个 结果，读取批处理的Transact-SQL语句的结果时。 （重写dbDataReader.NextResult（）。）

NextResult Advances the data reader to the next result, when reading the results of batch Transact-SQL statements. (Overrides dbDataReader.NextResult().)

推荐答案

如果您的语句是在/ proc返回多个结果集，例如，如果您有两个选择语句在单个命令的对象，那么你将获得两个结果集。

If your statement/proc is returning multiple result sets, For example, if you have two select statements in single Command object, then you will get back two result sets.

• NextResult 用于结果集之间移动。
• 读用于向前移动一个结果集中的记录。

• NextResult is used to move between result sets.
• Read is used to move forward in records of a single result set.

请看下面的例子：

如果你有一个进程，其主体是这样的：

If you have a proc whose main body is like:

.... Proc start

SELECT Name,Address FROM Table1

SELECT ID,Department FROM Table2

-- Proc End

执行上面的进程内会产生两个结果集。一为表1 或第一个SELECT语句等下一个选择语句。

Executing the above proc would produce two result sets. One for Table1 or first select statement and other for the next select statement.

在默认情况下第一个结果集将可用于读。如果你想要移动到第二个结果集，则需要 NextResult 。

By default first result set would be available for Read. If you want to move to second result set, you will need NextResult.

请参阅：检索数据使用DataReader

例子code：使用NextResult检索多个结果集

Example Code from the same link: Retrieving Multiple Result Sets using NextResult

static void RetrieveMultipleResults(SqlConnection connection)
{
    using (connection)
    {
        SqlCommand command = new SqlCommand(
          "SELECT CategoryID, CategoryName FROM dbo.Categories;" +
          "SELECT EmployeeID, LastName FROM dbo.Employees",
          connection);
        connection.Open();

        SqlDataReader reader = command.ExecuteReader();

        while (reader.HasRows)
        {
            Console.WriteLine("\t{0}\t{1}", reader.GetName(0),
                reader.GetName(1));

            while (reader.Read())
            {
                Console.WriteLine("\t{0}\t{1}", reader.GetInt32(0),
                    reader.GetString(1));
            }
            reader.NextResult();
        }
    }
}

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