[英]Exception when using MySqlBackup.NET to export database
我使用以下代碼備份MYSQL數據庫。
private void button2_Click(object sender, EventArgs e)
{
string file = "D:\\backup.sql";
//string conn = "server=localhost;user=root;pwd=qwerty;database=test;";
String str = @"server=192.168.1.219;database=abc;userid=sha;password='123';";
MySqlBackup mb = new MySqlBackup(str);
mb.ExportInfo.FileName = file;
mb.Export();
}
我的堆棧跟蹤如下 -
A first chance exception of type 'System.NullReferenceException' occurred in MySqlBackup.dll
System.Transactions Critical: 0 : <TraceRecord xmlns="http://schemas.microsoft.com/2004/10/E2ETraceEvent/TraceRecord" Severity="Critical"><TraceIdentifier>http://msdn.microsoft.com/TraceCodes/System/ActivityTracing/2004/07/Reliability/Exception/Unhandled</TraceIdentifier><Description>Unhandled exception</Description><AppDomain>TestAppMysqlDBConnect.vshost.exe</AppDomain><Exception><ExceptionType>System.NullReferenceException, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</ExceptionType><Message>Object reference not set to an instance of an object.</Message><StackTrace> at MySql.Data.MySqlClient.MySqlBackup.ExportExecute()
at MySql.Data.MySqlClient.MySqlBackup.Export()
at TestAppMysqlDBConnect.Form1.button2_Click(Object sender, EventArgs e) in C:\Users\Shashika\Documents\Visual Studio 2010\Projects\TestAppMysqlDBConnect\TestAppMysqlDBConnect\Form1.cs:line 52
at System.Windows.Forms.Control.OnClick(EventArgs e)
..
但是有一個例外,並且說有一個空引用異常。 當我通過C#程序將數據傳遞到數據庫時。 它被成功插入,沒有例外。 此異常僅在我嘗試通過C#程序備份數據庫時發生。 我使用了上面鏈接中的2個Dll文件。 那些是 - MySql.Data.dll MySqlBackup.dll
我無法解決這個異常。 請幫忙。
嘗試使用此功能(不要忘記您必須將MySqlBackup.dll添加到項目參考中):
public void Backup()
{
try
{
// Backup...
DateTime Time = DateTime.Now;
year = Time.Year;
month = Time.Month;
day = Time.Day;
hour = Time.Hour;
minute = Time.Minute;
second = Time.Second;
millisecond = Time.Millisecond;
//Save file to Path with the current date as a filename
string path;
path = txb_Path.Text + year + "-" + month + "-" + day + "--" + hour + "-" + minute + "-" + second + ".sql";
string file = path;
using (MySqlConnection conn = new MySqlConnection(connectionString))
{
using (MySqlCommand cmd = new MySqlCommand())
{
using (MySqlBackup mb = new MySqlBackup(cmd))
{
cmd.Connection = conn;
conn.Open();
mb.ExportToFile(file);
conn.Close();
}
}
}
//Done----
}
catch (Exception ex)
{
MessageBox.Show("Error , unable to backup!" + ex.Message);
}
}
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