Как правильно экранировать строку?

var fromUnixTime="123";
var toUnixTime="123";
var sqlquery = @"
SELECT player.id,
    TO_TIMESTAMP(player.""createTime"")::DATE as ""Дата регистрации"",
    TO_TIMESTAMP(payment.""createTime"")::DATE as ""Дата платежа"",
    payment.""currencyAmount"" as ""Бабки"",
    TO_TIMESTAMP(payment.""rollbackTime"")::DATE as ""Дата возврата бабок""
FROM player
    LEFT JOIN payment ON payment.""playerId"" = player.id
WHERE payment.""currencyAmount"" <> 0 AND 
    (player.""createTime"" >= "+fromUnixTime+" AND player.""createTime"" <= " + toUnixTime+")";

Система ругается на последную строку. Подскажите в чем проблема