对于复合外键，与主键的列组合是否需要/为什么引用表中的复合 UNIQUE 约束?

Each entry for [Table1] must have a unique [Name].

CREATE TABLE [Table1]
(
    [ID]    INT IDENTITY            NOT NULL PRIMARY KEY,
    [Name]  NVARCHAR(255) UNIQUE    NOT NULL CHECK(LTRIM(RTRIM([Name])) <> '')
);

INSERT INTO [Table1]([Name])
VALUES
('Name 1'),
('Name 2'),
('Name 3'),
('Name 4'),
('Name 5'),
('Name 6'),
('Name 7')

[Table2] 中的每个 [Value] 对于每个 [Table1ID] 都必须是唯一的.

Each [Value] in [Table2] must be unique for each [Table1ID].

CREATE TABLE [Table2]
(
    [ID]        INT IDENTITY    NOT NULL    PRIMARY KEY,
    [Table1ID]  INT             NOT NULL    FOREIGN KEY REFERENCES [Table1]([ID]),
    [Value]     NVARCHAR(255)   NOT NULL    CHECK(LTRIM(RTRIM([Value])) <> ''),

    --UNIQUE([ID], [Table1ID]),
    UNIQUE([Table1ID], [Value])
);

INSERT INTO [Table2]([Table1ID], [Value])
VALUES
(1, 'Entry 1'),
(1, 'Entry 2'),
(1, 'Entry 3'),
(1, 'Entry 4'),
(3, 'Entry 5'),
(3, 'Entry 6'),
(3, 'Entry 7')

[Table1ID] 和 [Table2ID] 中的每个组合 [Table3] 必须在 [Table2] 中具有匹配的组合 (我假设 [Table1ID] 和 [Table2ID] 的两个 FOREIGN KEY 将是多余的，如果复合外键是否到位?).

Each combination of [Table1ID] and [Table2ID] in [Table3] must have a matching combination in [Table2] (I'm assuming that the two FOREIGN KEYs for [Table1ID] and [Table2ID] would be superfluous if the composite FOREIGN KEY is in place?).

CREATE TABLE [Table3]
(
    [ID]        INT IDENTITY    NOT NULL,
    [Table1ID]  INT             NOT NULL    FOREIGN KEY REFERENCES [Table1]([ID]),
    [Table2ID]  INT             NOT NULL    FOREIGN KEY REFERENCES [Table2]([ID]),

    FOREIGN KEY ([Table2ID], [Table1ID]) REFERENCES [Table2](ID, [Table1ID])
);

INSERT INTO [Table3]([Table2ID], [Table1ID])
VALUES
(5, 3)

[Table3] 中的复合 FOREIGN KEY 约束是问题所在.如果 [Table2] 中被注释掉的 UNIQUE 约束没有被注释，则 [Table3] 可以成功创建.如果不是，[Table3] 的创建将失败，提示引用的表中没有与外键中的引用列列表匹配的主键或候选键".

That composite FOREIGN KEY constraint in [Table3] is the problem. If that commented-out UNIQUE constraint in [Table2] is uncommented, [Table3] can be created successfully. If it is not, the creation of [Table3] will fail saying "There are no primary or candidate keys in the referenced table that match the referencing column list in the foreign key".