System.Data.Common.DbDataReader [英] System.Data.Common.DbDataReader

问题描述

如果我使用这个类做了

SELECT * FROM ...

针对数据库，我应该用什么方法或变量此类只是为了给我从SQL语句？

statement against a database, what method or variable of this class should I use just to give me a dump of the output from the SQL statement?

推荐答案

在使用的DbDataReader你需要遍历所有的结果是这样的：

When using a DbDataReader you'll need to iterate over all the results like this:

using (DbDataReader dataReader = dbCommand.ExecuteReader())
{
    while (dataReader.Read())
    {
        // Get the values of the fields in the current row
        // For example, if the first column is a string...
        string firstColumn = dataReader.GetString(0);
    }

    dataReader.Close();
}

如果你试图把结果输出到一个文件中，一个非常幼稚的做法是这样的：

If you are trying to output the results to a file, a very naive approach would be something like this:

using (StreamWriter streamWriter = new StreamWriter(path))
{
    using (DbDataReader dataReader = command.ExecuteReader())
    {
        while (dataReader.Read())
        {
            for (int index = 0; index < dataReader.FieldCount; index++)
            {
                streamWriter.Write(dataReader.GetValue(index));

                if (index < dataReader.FieldCount - 1)
                {
                    streamWriter.Write(',');
                }
                else
                {
                    streamWriter.WriteLine();
                }
            }
        }

        dataReader.Close();
    }

    streamWriter.Close();
}

这将产生一个基本的CSV文件。

This will generate a basic CSV file.

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