count method
Returns total count of matched rows.
Implementation
@override
Future<int> count() async {
final sql = grammar.compileAggregate(
_getQueryComponents(),
{'function': 'COUNT', 'column': '*'},
);
final aggregateBindings = [
..._fromBindings,
..._joinBindings,
..._whereBindings,
..._havingBindings,
];
final result = await connection.execute(sql, aggregateBindings);
return result.data.first['aggregate'] as int;
}