我在多个表视图上遇到触发器问题。
让我解释一下: 我有2个数据表,主键和表事件有很多关系。
CREATE TABLE Club
(
name_of_club varchar(50) PRIMARY KEY,
adress varchar(50) NOT NULL
)
CREATE TABLE Band
(
name_of_band varchar(50) PRIMARY KEY,
members int NOT NULL
)
CREATE TABLE Event
(
name_of_club varchar(50) NOT NULL,
name_of_band varchar(50) NOT NULL,
data date NOT NULL,
CONSTRAINT PK_Event PRIMARY KEY
(
name_of_club,
name_of_band
),
FOREIGN KEY (name_of_club) REFERENCES Club (name_of_club),
FOREIGN KEY (name_of_band) REFERENCES Band (name_of_band)
)
现在我可以添加一些值:
insert into Club (name_of_club, adress)
values
('Big London Club', 'Londyn, Baker Street 12'),
('Espana Time', 'Barcelona, Diego 15'),
('Wwa', 'Warszawa, Sezonowa 82/14'),
('Szwalnia', 'Łódź, Piotrkowska 20/2');
insert into Band (name_of_band, members)
values
('Arctic Monkeys', 5),
('Random Guys', 3),
('TILT', 10),
('Joke Time', 2);
insert into Event (name_of_club, name_of_band, data)
values
('Big London Club', 'Arctic Monkeys', '2015-01-25'),
('Wwa', 'TILT', '2015-01-28'),
('Szwalnia', 'Joke Time', '2015-02-10');
让我们创建视图:
CREATE VIEW Events AS
SELECT Club.name_of_club, adress, Band.name_of_band, members, data
FROM Event
JOIN Club ON Club.name_of_club = Event.name_of_club
JOIN Band ON Band.name_of_band = Event.name_of_band
现在我必须为INSERT操作创建一个触发器。
1 *在视图中插入行时,我需要检查是否存在行:
是 - >显示错误
否 - >转到第2点
2 *检查插入时是否有俱乐部和带有指定名称的乐队。
3 *当该行包含俱乐部的数据且该乐队不在时 表,化妆基表。在最后化妆事件表 代表多对多的关系。现在应该会更好。
编辑:触发点工作
答案 0 :(得分:1)
可以使用INSTEAD OF TRIGGER来完成,触发器应该是这样的:
CREATE TRIGGER InsteadOfEventInsert ON Events INSTEAD OF INSERT
AS
BEGIN
DECLARE @name_of_club VARCHAR(50),
@name_of_band VARCHAR(50),
@data DATE,
@members int
SELECT @name_of_club = name_of_club,
@name_of_band = name_of_band,
@data = data,
@members = members
FROM INSERTED
IF NOT EXISTS( SELECT 1
FROM Events
WHERE name_of_club = @name_of_club
AND name_of_band = @name_of_band
AND data = @data
)
BEGIN
IF NOT EXISTS(SELECT 1 FROM Club WHERE name_of_club = @name_of_club)
INSERT INTO Club VALUES(@name_of_club, @members)
IF NOT EXISTS(SELECT 1 FROM Band WHERE name_of_band = @name_of_band)
INSERT INTO Band VALUES(@name_of_band, @members)
INSERT INTO [Event] SELECT name_of_club, name_of_band, data FROM INSERTED
END
END
我建议只为Club和Band添加一个INT标识列,而不是将名称作为主键。
答案 1 :(得分:0)
示例插入:
INSERT INTO Events values ('Test Club', 'Test Adress', 'Test Band', 5, '2015-01-01')
触发:
CREATE TRIGGER InsteadOfEventInsert ON Events INSTEAD OF INSERT
AS
BEGIN
DECLARE @name_of_club VARCHAR(50),
@adress varchar(50),
@name_of_band VARCHAR(50),
@members int,
@data date
SELECT @name_of_club = name_of_club,
@adress = adress,
@name_of_band = name_of_band,
@members = members,
@data = data
FROM INSERTED
IF NOT EXISTS( SELECT 1
FROM Events
WHERE name_of_club = @name_of_club
AND adress = @adress
AND name_of_band = @name_of_band
AND data = @data
)
BEGIN
IF NOT EXISTS(SELECT 1 FROM Club WHERE name_of_club = @name_of_club)
INSERT INTO Club VALUES(@name_of_club, @adress)
IF NOT EXISTS(SELECT 1 FROM Band WHERE name_of_band = @name_of_band)
INSERT INTO Band VALUES(@name_of_band, @members)
END
INSERT INTO [Event] SELECT name_of_club, name_of_band, data FROM INSERTED
END
看起来应该是这样的吗?
编辑:它有效;)