说我有以下表格:
CREATE TABLE [Weeks]
(
[Id] INT NOT NULL IDENTITY,
CONSTRAINT [PK_Weeks] PRIMARY KEY ([Id])
);
CREATE TABLE [Days]
(
[Id] INT NOT NULL IDENTITY,
[WeekId] INT NULL,
CONSTRAINT [PK_Days] PRIMARY KEY ([Id]),
CONSTRAINT [FK_Days_Weeks_WeekId]
FOREIGN KEY ([WeekId]) REFERENCES [Weeks] ([Id])
);
CREATE TABLE [ReplacedDayInWeek]
(
[Id] INT NOT NULL IDENTITY,
[WeekId] INT NOT NULL,
[DayId] INT NOT NULL,
[ReplacedDayId] INT NOT NULL,
CONSTRAINT [PK_ReplacedDayInWeek] PRIMARY KEY ([Id]),
CONSTRAINT [FK_ReplacedDayInWeek_Days_DayId]
FOREIGN KEY ([DayId]) REFERENCES [Days] ([Id]),
CONSTRAINT [FK_ReplacedDayInWeek_Weeks_WeekId]
FOREIGN KEY ([WeekId]) REFERENCES [Weeks] ([Id]),
CONSTRAINT [FK_ReplacedDayInWeek_Weeks_ReplacedWeekId]
FOREIGN KEY ([ReplacedWeekId]) REFERENCES [Weeks] ([Id])
);
表ReplacedDayInWeek包含特定周的一天,由另一天替换。
我如何创建一个SQL约束(或者可能是另一个基于SQL的解决方案),以确保我只能使用与DayInWeek
同一周的DayId
将行插入WeekId
?
我正在寻找对源数据库进行最少量更改的解决方案。我更喜欢在存储过程之上更改一个表或表。
这种数据结构对我来说毫无意义。您有两个表中的天和周之间的映射。
你应该只将一周存储在一个表中,然后在另一个表中查找。
也就是说,您可以使用两个表之间的日/周额外约束来执行您想要的操作:
CREATE TABLE [Days]
(
[Id] INT NOT NULL IDENTITY,
[WeekId] INT NULL,
CONSTRAINT [PK_Days] PRIMARY KEY ([Id]),
CONSTRAINT [FK_Days_Weeks_WeekId]
FOREIGN KEY ([WeekId]) REFERENCES [Weeks] ([Id]),
CONSTRAINT UNQ_Days_WeekId_Id UNIQUE (WeekId, Id)
);
CREATE TABLE [DaysInWeek]
(
[Id] INT NOT NULL IDENTITY,
[WeekId] INT NOT NULL,
[DayId] INT NOT NULL,
CONSTRAINT [PK_DaysInWeek] PRIMARY KEY([Id]),
CONSTRAINT [FK_DaysInWeek_Days_WeekId_DayId]
FOREIGN KEY (WeekId, DayId) REFERENCES Days(WeekId, Id),
CONSTRAINT [FK_DaysInWeek_Weeks_WeekId]
FOREIGN KEY ([WeekId]) REFERENCES [Weeks] ([Id])
);