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我使用.NET连接器连接到MySQL。 在我的应用程序有使用相同的连接线程数,所以如果一个了MySqlDataReader还没有结束,有些线程试图执行一个查询它给出了错误:MySQL的 - 多个结果集
There is already an open DataReader associated with this Connection which must be closed first.
将永远在那里在MySQL支持多种结果集或其名称?
public class DatabaseConnection
{
private MySqlConnection conn;
public void Connect(string server, string user, string password, string database, int port = 3306)
{
string connStr = String.Format("server={0};user={1};database={2};port={3};password={4};charset=utf8",
server, user, database, port, password);
conn = new MySqlConnection(connStr);
conn.Open();
}
private MySqlCommand PrepareQuery(string query, object[] args)
{
MySqlCommand cmd = new MySqlCommand();
cmd.Connection = conn;
for (int i = 0; i < args.Length; i++)
{
string param = "{" + i + "}";
string paramName = "@DBVar_" + i;
query = query.Replace(param, paramName);
cmd.Parameters.AddWithValue(paramName, args[i]);
}
cmd.CommandText = query;
return cmd;
}
public List<Dictionary<string, object>> Query(string query, params object[] args)
{
MySqlCommand cmd = PrepareQuery(query, args);
MySqlDataReader reader = cmd.ExecuteReader();
List<Dictionary<string, object>> rows = new List<Dictionary<string, object>>();
while (reader.Read())
{
Dictionary<string, object> row = new Dictionary<string, object>();
for (int i = 0; i < reader.FieldCount; i++)
{
row.Add(reader.GetName(i), reader.GetValue(i));
}
rows.Add(row);
}
reader.Close();
return rows;
}
public object ScalarQuery(string query, params object[] args)
{
MySqlCommand cmd = PrepareQuery(query, args);
return cmd.ExecuteScalar();
}
public void Execute(string query, params object[] args)
{
MySqlCommand cmd = PrepareQuery(query, args);
cmd.ExecuteNonQuery();
}
public void Close()
{
conn.Close();
}
}
的我如何使用这样的一个例子:
DatabaseConnection Conn = new DatabaseConnection();
Conn.Connect("localhost", "root", "", "foogle");
var rows = conn.Query("SELECT * FROM `posts` WHERE `id` = {0}", postID);
foreach (var row in rows)
{
Console.WriteLine(row["title"]); // Writes the post's title (example)
}
我不会说这是由于MySQL的。看起来更像是MySQLDataReader控件的限制。 – 2010-07-23 19:57:31
如果MySQL支持这个,我可以在他们的网站上找到这个功能..:\ – 2010-07-23 19:58:57
你可以发布你的代码吗? – 2010-07-24 07:13:43