Question

我正在使用Roland Bock's sqlpp11库进行mysql查询，并使用Howard Hinnant's date库在我的项目中进行日期操作。

在我的某个更新查询中收到以下错误。

/usr/local/include/sqlpp11/rhs_wrap.h: In instantiation of ‘struct sqlpp::rhs_wrap_t<date::year_month_day, false>’:
/usr/local/include/sqlpp11/assignment.h:63:12:   required from ‘struct sqlpp::assignment_t<sqlpp::column_t<changestreet::Goals, changestreet::Goals_::GoalEndDate>, date::year_month_day>’
sqlOperations/sqlppDbConnection.cpp:286:65:   required from ‘bool setEmergencyFundGoal(T1, T2, T2, T3, T3) [with T1 = int; T2 = const char*; T3 = double]’
main.cpp:705:113:   required from here
/usr/local/include/sqlpp11/rhs_wrap.h:119:43: error: no type named ‘_traits’ in ‘class date::year_month_day’
     using _traits = typename Expr::_traits;

这是更新声明

auto efGoal = db_cs.run(update(g).set(g.goalAmount = emergencyFund,
                                                  g.goalEndDate = contributionEndDate, // Line number 286
                                                  g.goalContributionStartDate = currentDate(),
                                                  g.goalContributionEndDate = contributionEndDate,
                                                  g.goalInitialContribution = initialContribution,
                                                  g.goalMaximumAchievableAmount = emergencyFund,
                                                  g.goalCreatedOn = currentDateTime(),
                                                  g.goalUpdatedOn = currentDateTime()
                                                  ).where(g.goalName == goalName
                                                          and g.goalType == goalType
                                                          and g.usersUserId == userId)
                                    );

这是rhs中使用的值

auto contributionEndDate = lastDateOfMonth(currentDate(), date::months{contributionTenure}) ;

以下是贡献lastDateOfMonth()功能的定义。

date::year_month_day lastDateOfMonth(date::year_month_day givenDate, date::months monthsNum) {
    date::year_month_day newDate = year_month_day{givenDate} + monthsNum;
    newDate = newDate.year()/newDate.month()/last;
    return newDate;
}

currentDate()函数

date::year_month_day currentDate() {
    auto currentTime = system_clock::now();
    auto currentDate = floor<days>(currentTime);
    return currentDate;
}

列名goal_end_date在mysql表结构中的类型为DATE。

Answer 1

我需要将mysql数据类型从DATE更改为DATETIME，之后system_clock::time_point类型变量赋值变量就像魅力一样。

它也适用于具有变量赋值类型DATE的mysql system_clock::day_point dataype。

P.S：我需要修改返回类型为syste_clock::time_point的两个给定功能。

错误：'class date :: year_month_day'中没有名为'_traits'的类型？

1 个答案: