c# - MySqlConnection.StateChange 永远不会获取

Question

MySqlConnection.StateChange 是如何工作的？

我有以下代码。

conn.StateChange += ConnectionStateChanged;

private void ConnectionStateChanged(Object sender, StateChangeEventArgs e) {
    switch (e.CurrentState) {
    // is never equal to Fetching
    }
}

public DataTable Query(string query) {
    DataTable dt = new DataTable();

    using (MySqlDataAdapter a = new MySqlDataAdapter(query, conn)) {
        try {
            a.SelectCommand.CommandTimeout = 5;
            a.Fill(dt);
        } catch {
            return null;
        }
    }

    return dt;
}

为什么 ConnectionStateChanged 永远不会通过 ConnectionState.Fetching 或 ConnectionState.Executing 调用？

Answer 1

好吧，我可能会误解msdn ，但这些状态似乎没有实现(枚举值只是“保留”，即使在 .net 4.5 中也是如此):

Executing The connection object is executing a command. (This value is reserved for future versions of the product.)

和

Fetching The connection object is retrieving data. (This value is reserved for future versions of the product.)