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);
}
public void Commit(System.Data.SQLite.SQLiteDatabase db = null)
{
if (db == null)
{
db = this.db;
}
if (db == null)
{
return;
}
db.Commit();
}