计算本周特定日期的行数 sqlite

Question

我想创建一个查询，返回本周特定日期的行数。例如，如果 dayNumber = 1，它应该返回 BookSaveTime 为星期一的图书数。如果dayNumber = 2，它应该返回星期二的计数，等等。

var week = DateTime.Today.AddDays(-(((int)DateTime.Today.DayOfWeek+6)%7));
return database.ExecuteScalar<int>("SELECT count(*) FROM Book WHERE BookSaveTime > ?;", week);

目前，此查询返回自一周开始以来的书籍数量 - 但我不知道如何修改它以返回给定指定日期的计数 - 例如，星期一或星期二。

public MyAppSQLiteDatabase()
{
    try
    {
        database = DependencyService.Get<ISQLiteService>().GetConnection(DbFileName);
        database.CreateTable<Book>();

        CurrentState = "Database created";

    }
    catch (SQLiteException ex)
    {
        CurrentState = ex.Message;
    }
}

public int GetDailyCount(int dayNumber){
    var day = DateTime.Today.AddDays(-(((int)DateTime.Today.DayOfWeek+6)%dayNumber));
    return database.ExecuteScalar<int>("SELECT count(*) FROM Book WHERE BookSaveTime = ?;", day );
}

书籍类：

public class Book: INotifyPropertyChanged
{
    [PrimaryKey, AutoIncrement]
    public int ID { get; set; }
    private DateTime bookSaveTime;
    public DateTime BookSaveTime
    {
        get
        {
            return bookSaveTime;
        }
        set
        {
            if (bookSaveTime != value)
            {
                bookSaveTime= value;
                OnPropertyChanged("BookSaveTime");
            }
        }
    }
}
    

Answer 1

要查找特定的工作日信息，您的查询应如下所示 =>

SELECT * FROM
(SELECT *, cast (strftime('%w', BookSaveTime) as integer) AS WeekDay
FROM BOOK) T1
WHERE T1.WeekDay=1; --Weekday=1 is MONDAY

要查找特定日期的计数，请使用下面的查询

SELECT WeekDay,COUNT(*) AS WeekDayCount FROM
(SELECT *,strftime('%w',BookSaveTime) AS WeekDay
FROM BOOK) T1
GROUP BY T1.WeekDay

注意：您可以在 T1 中添加 WHERE BookSaveTime BETWEEN '2010-01-01' AND '2010-01-31' 以选择特定日期范围内的数据。 DB-Fiddle中的演示代码。