createTable method Null safety
Creates the TransactionRepository.table if it does not exist.
Implementation
Future<void> createTable() async {
_db.execute('''CREATE TABLE IF NOT EXISTS $table (
$columnId STRING PRIMARY KEY NOT NULL,
$columnMerkelProof BLOB,
$columnVersion INTEGER NOT NULL,
$columnAddress BLOB NOT NULL,
$columnContents BLOB NOT NULL,
$columnAssetRef TEXT NOT NULL,
$columnBlockId TEXT,
$columnTimestamp INTEGER NOT NULL,
$columnSignature TEXT NOT NULL
);
''');
}