public static SQLiteDatabase CreateInMemoryDB(string filename)
{
// returns a copy of a database in memory
// create an empty memory db first
SQLiteDatabase memdb = new SQLiteDatabase(":memory:");
try
{
// open an existing on disk db
SQLiteDatabase ondiskdb = new SQLiteDatabase(filename);
ondiskdb.Open();
// get user & schema version
int user_version = ondiskdb.GetUserVersion();
int schema_version = ondiskdb.GetSchemaVersion();
// get text encoding
string text_encoding = ondiskdb.GetTextEncoding();
// get sql for creating structures
string sql = "select sql from sqlite_master where name not like 'sqlite_%'";
DataTable structure = ondiskdb.Select(sql);
// get user tables
sql = "select name from sqlite_master where type = 'table' and name not like 'sqlite_%'";
DataTable usertables = ondiskdb.Select(sql);
// crate identically structures in memmory db
memdb.Open();
foreach (DataRow row in structure.Rows)
{
memdb.DBCommand.CommandText = row[0].ToString();
memdb.DBCommand.ExecuteNonQuery();
}
// set user & schema version
memdb.SetUserVerion(user_version);
memdb.SetSchemaVerion(schema_version);
// set text encoding
memdb.SetTextEncoding(text_encoding);
user_version = memdb.GetUserVersion();
text_encoding = memdb.GetTextEncoding();
// close on disk db
ondiskdb.Close();
// attach on disk db to memory db
memdb.AttachDatabase(filename, "ondisk");
memdb.BeginTransaction();
foreach (DataRow row in usertables.Rows)
{
memdb.DBCommand.CommandText = "insert into main." + row[0].ToString() + " select * from ondisk." + row[0].ToString();
memdb.DBCommand.ExecuteNonQuery();
}
memdb.Commit();
memdb.DetachDatabase("ondisk");
memdb.DiskFileName = filename;
}
catch (Exception ex)
{
Console.WriteLine(ex.Message);
}
return(memdb);
}
protected System.Data.SQLite.SQLiteDatabase OpenDatabase(string name, string defaultdatabasedirectory, bool inmemory)
{
System.Data.SQLite.SQLiteDatabase db = null;
try
{
// check if database path exists --> create if not
if (!Directory.Exists(defaultdatabasedirectory))
{
Directory.CreateDirectory(defaultdatabasedirectory);
}
// check if database is already on disk
DBPath = defaultdatabasedirectory;
if (!File.Exists(Path.Combine(DBPath, name)))
{
// create one on disk
System.Data.SQLite.SQLiteDatabase dbn = new System.Data.SQLite.SQLiteDatabase(Path.Combine(DBPath, name));
// open database
dbn.Open();
// set user version
dbn.SetUserVerion(UserVersion);
// set auto vacuum mode to full
dbn.SetAutoVacuum(AUTOVACUUMMODE.FULL);
dbn.Close();
}
// check for in-memory database --> open from disk, if not
if (inmemory)
{
db = System.Data.SQLite.SQLiteDatabase.CreateInMemoryDB(Path.Combine(DBPath, name));
}
else
{
db = new System.Data.SQLite.SQLiteDatabase(Path.Combine(DBPath, name));
db.Open();
}
// get version info
int v = db.GetUserVersion();
// do upgrade stuff here
}
catch (Exception ex)
{
Console.WriteLine("Error initilalizing database: " + ex.Message);
throw new TypeInitializationException(this.GetType().Name, ex);
}
return(db);
}
