read a .db file in C# | 易学教程

问题

 string Path = @"c:\Database\Mydatabase.db";

     string myConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + Path + ";Extended Properties=Paradox 5.x;";

    // Define the database query    
    string mySelectQuery = "SELECT id,name FROM people WHERE id < 3;";

    // Create a database connection object using the connection string    
    OleDbConnection myConnection = new OleDbConnection(myConnectionString);

    // Create a database command on the connection using query    
    OleDbCommand myCommand = new OleDbCommand(mySelectQuery, myConnection);

    // Open the connection    
    myCommand.Connection.Open();

    // Create a database reader    
    OleDbDataReader myReader = myCommand.ExecuteReader(CommandBehavior.CloseConnection);

The Error is at myCommand.Connection.Open(); and it says: 'c:\Database\Mydatabase.db' is not a valid path. Make sure that the path name is spelled correctly and that you are connected to the server on which the file resides.

I am trying to read a .db file in C#. However, I am getting an error, I am sure that file is located there, the error does not make sense for me. Could you please help me ? Or How can I read a .db(paradox) database file in C# ?

EDIT: string Path = @"c:\Database\";

The Error for this case is "The Microsoft Jet database engine could not find the object 'people'. Make sure the object exists and that you spell its name and the path name correctly."

If I change it like that, How can C# find which database file is gonna be used ? Since, I did not specify file name which is "Mydatabase.db" at anywhere

回答1:

Confirmed it is an SQLite database, I just downloaded it on my phone and viewed it with an SQLite viewer.

You will need to download an ADO.NET provider for SQLite:

"Official" version (from SQLite, not MS)

http://system.data.sqlite.org/index.html/doc/trunk/www/index.wiki

Older version

http://sqlite.phxsoftware.com/

回答2:

if the application cannot see the file than chances are it's a security issue. while "you" can access the file. the application cannot.

is this a web application? if so, then this is the problem. asp.net/IIS cannot see outside of its virtual directory. In which case you either need to elevate/modify privileges of the asp.net user account to access the file, or move the database file within the virtual directory. This is a good candidate for the App_Data directory.

回答3:

Try one of these connection strings instead.

回答4:

According to this site, you should only specify the folder name, not the db file.

Please note that you should only specify the folder where the database resides. Not the database name itself.

The linked MSDN article says that Jet 4.0 Service Pack 5 should be used if you want to update the data, otherwise it may be read-only. In any case I would recommend installing the service pack.

来源：https://stackoverflow.com/questions/11021455/read-a-db-file-in-c-sharp

标签

.net

database

paradox