Anthony D Anthony D - 2 months ago 21
C# Question

Setting single user mode to restore backup

I have the following function:

public void RestoreDatabase(String databaseName, String backUpFile,
String serverName, String userName, String password)
{
SqlConnection.ClearAllPools();
ServerConnection connection = new ServerConnection
(serverName, userName, password);
Server sqlServer = new Server(connection);
Restore rstDatabase = new Restore();
rstDatabase.Action = RestoreActionType.Database;
rstDatabase.Database = databaseName;
BackupDeviceItem bkpDevice = new BackupDeviceItem
(backUpFile, DeviceType.File);
rstDatabase.Devices.Add(bkpDevice);
rstDatabase.ReplaceDatabase = true;
rstDatabase.SqlRestore(sqlServer);
}


I was trying to set the DB to single user mode first, before restoring the backup. I tried this code:

private string singleUserCmd = "alter database db-name set SINGLE_USER";
private string multiUserCmd = "alter database db-name set MULTI_USER";

private void SetSingleUser(bool singleUser,
SqlConnectionStringBuilder csb)
{
string v;
if (singleUser)
{
v = singleUserCmd.Replace("db-name", csb.InitialCatalog);
}
else
{
v = multiUserCmd.Replace("db-name", csb.InitialCatalog);
}
SqlCommand cmd = new SqlCommand(v, new SqlConnection
(csb.ToString()));
try
{
cmd.Connection.Open();
cmd.ExecuteNonQuery();
}
finally
{
cmd.Connection.Close();
}
}


The problem seems to be that single user mode is for that connection, preventing anyone else from doing anything. I need it to be for the connection that restores the backup.

Answer

The restore would need to occur on the connection which placed the DB into single user mode, so why not make your SetSingleUser function return the opened SqlConnection it executed on and then have your Restore code take in and use the same opened connection.

private string singleUserCmd = "alter database db-name set SINGLE_USER";
private string multiUserCmd = "alter database db-name  set MULTI_USER";

private SqlConnection SetSingleUser(bool singleUser, SqlConnectionStringBuilder csb)
{
    string v;
    if (singleUser)
    {
        v = singleUserCmd.Replace("db-name", csb.InitialCatalog);
    }
    else
    {
        v = multiUserCmd.Replace("db-name", csb.InitialCatalog);
    }
    SqlConnection connection = new SqlConnection(csb.ToString());
    SqlCommand cmd = new SqlCommand(v, connection);

        cmd.Connection.Open();
        cmd.ExecuteNonQuery();

    return connection;
}