Question

我正在尝试从具有2行的MYSQL表中检索数据，但是仅返回第一行。使用的SQL语句非常简单sqlQuery =“ SELECT * FROM table”

使用下面的代码，该类仅返回找到的第一个值

    private ArrayList dbRead(String sqlQuery, String classQuery)
    {
        ArrayList dbCategoryResults = new ArrayList();

    // *** CONNECT TO DATABASE
        Console.WriteLine("** Database Connection: Connecting to database");
        MySqlConnection dbConnection = new MySqlConnection(dbStringConnection);

        try
        {
            dbConnection.Open();
            Console.WriteLine("** Database Connection: Connected to database server");

            // *** READ FROM DATABASE
            MySqlCommand command = new MySqlCommand(sqlQuery, dbConnection);
            MySqlDataReader dataReader = command.ExecuteReader();

            if (dataReader.Read())
            {
                if (classQuery == "categories")
                {
                    //String det = dataReader[1].ToString();

                    dbCategoryResults.Add(dataReader[1]);

                    Console.WriteLine("Found " + dbCategoryResults.Count);

                    return dbCategoryResults;
                }
            }
            dataReader.Close();

            command.Dispose();
            dbConnection.Close();
        }
        catch (MySqlException e)
        {
            Console.WriteLine(e.ToString());
            MessageBox.Show(e.Message, "Database Error", MessageBoxButtons.OK, MessageBoxIcon.Error);
        }

        // CLOSE DATABASE
        try
        {
            dbConnection.Close();
        }
        catch (Exception e)
        {
            Console.WriteLine(e.ToString());
        }

        return null;
    }

Answer 1

这很简单

// 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));
}

如果您想要行数，则可以始终使用DataTable甚至在while循环中使用计数。 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"]);
}

DataReader.Read（）仅返回一个值

1 个答案: