DataReader.Read()只返回一个值

它很简单

// Always call Read before accessing data.
// Advances the MySqlDataReader to the next record.
// returns true if it finds a record
while (dataReader.Read()) 
{
   // depending on your query
   Console.WriteLine(myReader.GetInt32(0) + ", " + myReader.GetString(1));
}

如果你想要行数,你总是可以使用一个DataTable甚至只是在while循环中使用一个计数.DataTable示例:

DataTable dt = new DataTable();
dt.Load(reader);

Console.WriteLine("Rows returned : " + dt.Rows.Count); 

foreach(DataRow dr in dt.Rows)
{
     Console.WriteLine(dr["SomeResultingColumn"]);
}