I have two tables: Ticket and TicketRelation. I am trying to relate 2 Tickets using the TicketRelation table.
I want to add a cascade constraint to both foreign keys.
I am using SQL Server Management Studio to add the constraints but I get this error:
Introducing FOREIGN KEY constraint 'FK_destiny_ticket' on table 'ticketRelation' may cause cycles or multiple cascade paths. Specify ON DELETE NO ACTION or ON UPDATE NO ACTION, or modify other FOREIGN KEY constraints.
I also tried to do this with a trigger, but I am not sure how to define it.
Here I provide the tables definitions:
This is the base entity TICKET
CREATE TABLE ticket
(
ticket_id BIGINT,
some_data VARCHAR (50),
CONSTRAINT PK_ticket PRIMARY KEY (ticket_id)
);
and the relational table TICKETRELATION
CREATE TABLE ticketRelation
(
origin_ticket BIGINT,
destiny_ticket BIGINT,
relation_data VARCHAR (50),
CONSTRAINT PK_ticket_relation PRIMARY KEY (origin_ticket, destiny_ticket),
CONSTRAINT FK_origin_ticket FOREIGN KEY (origin_ticket)
REFERENCES ticket(ticket_id),
CONSTRAINT FK_destiny_ticket FOREIGN KEY (destiny_ticket)
REFERENCES ticket(ticket_id),
)
I want to add an ON DELETE CASCADE constraint to both foreign keys:
CONSTRAINT FK_origin_ticket FOREIGN KEY (origin_ticket)
REFERENCES ticket(ticket_id)
ON DELETE CASCADE, -- I want to add this --
CONSTRAINT FK_destiny_ticket FOREIGN KEY (origin_ticket)
REFERENCES ticket(ticket_id)
ON DELETE CASCADE, -- and this --
Related
I am applying a foreign key constraint to a table(datareal.official). Should I always refer to the same columns in the primary key of the other tabel (datareal.officialcarriage). Or could I theoretically also use difference in the reference table?
ALTER TABLE datareal.official
ADD CONSTRAINT FK_carriage FOREIGN KEY
(target,goal)
REFERENCES datareal.officialcarriage (target,goal)
ON DELETE CASCADE
ON UPDATE CASCADE
I tried to create foreign key with ON DELETE CASCADE constraint that references the same table, but that deemed to be impossible due to the following error:
Introducing FOREIGN KEY constraint 'FK_Employees_Employees' on table
'Employees' may cause cycles or multiple cascade paths.
How should I be defining my table? My requirements are:
Employee might not have a manager
When employee who is a manager is deleted all of his employees are also deleted
CREATE TABLE [dbo].[Employees]
(
[EmployeeId] INT NOT NULL IDENTITY(1,1),
[ManagerId] INT NULL,
--...
CONSTRAINT [PK_Employees] PRIMARY KEY ([EmployeeId]),
CONSTRAINT [FK_Employees_Employees] FOREIGN KEY ([ManagerId])
REFERENCES [dbo].[Employees] ([EmployeeId]) -- ON DELETE CASCADE
)
ALTER TABLE `SWIMMER`
ADD CONSTRAINT `fk5` FOREIGN KEY (`CoachID`, `Country`) REFERENCES `TEAMMEMBER` (`MemberID`, `Country`),
ADD CONSTRAINT `fk1` FOREIGN KEY (`MemberID`, `Country`) REFERENCES `TEAMMEMBER` (`MemberID`, `Country`);
I'm using this SQL query and unfortunately it runs but the designer mode in phpmyadmin isn't showing up the relation between the TeamMember table and the Swimmer table which is a supertype and subtype relation in this database. Please Let me know if you can do this kind of sql query or you need to make some other connection.
ALTER TABLE `SWIMMER`
ADD CONSTRAINT `fk5` FOREIGN KEY (`CoachID`, `Country`) REFERENCES `TEAMMEMBER` (`MemberID`, `Country`),
ADD CONSTRAINT `fk1` FOREIGN KEY (`MemberID`, `Country`) REFERENCES `TEAMMEMBER` (`MemberID`, `Country`);
I am trying to add foreign key to my existing column using below query
ALTER TABLE Sub_Category_Master
ADD FOREIGN KEY (Category_ID) REFERENCES Category_Master(Category_ID)
but I'm getting an error
The ALTER TABLE statement conflicted with the FOREIGN KEY constraint "FK__Sub_Categ__Categ__5812160E". The conflict occurred in database "shaadikarbefikar_new", table "shaadikarbefikar.Category_Master", column 'Category_ID'.
Well, the error clearly tells you that Category_ID in your Sub_Category_Master table contains some values that are not present in Category_Master (column Category_ID). But that's exactly the point of having a foreign key constraint - making sure your child table (Sub_Category_Master) only uses defined values from its parent table.
Therefore, you must fix those "voodoo" values first, before you're able to establish this foreign key relationship. I would also strongly recommend to explicitly name that constraint yourself, to avoid those system-generated, but not really very useful constraint names like FK__Sub_Categ__Categ__5812160E:
ALTER TABLE Sub_Category_Master
ADD CONSTRAINT FK_SubCategoryMaster_CategoryMaster
FOREIGN KEY (Category_ID) REFERENCES Category_Master(Category_ID)
ALTER TABLE Sub_Category_Master
ADD CONSTRAINT FKSub_Category_Master_Category_ID FOREIGN KEY (Category_ID)
REFERENCES Category_Master(Category_ID);
CREATE TABLE Orders
(
OrderID int NOT NULL,
OrderNumber int NOT NULL,
PersonID int,
PRIMARY KEY (OrderID),
CONSTRAINT FK_PersonOrder
FOREIGN KEY (PersonID) REFERENCES Persons(PersonID)
);
I have the following T-SQL to create 3 SQL tables:
create table dbo.Posts
(
Id int identity not null
constraint PK_Posts_Id primary key clustered (Id),
Active bit not null
constraint DF_Posts_Active default (0)
);
create table dbo.PostsLocalized
(
Id int not null,
Culture int not null
constraint CK_PostsLocalized_Culture check ([Culture] in ('1', '2', '3')),
[Text] nvarchar (200) not null,
constraint PK_PostsLocalized_Id_Culture primary key clustered (Id, Culture)
);
create table dbo.Tags
(
Id int identity not null
constraint PK_Tags_Id primary key clustered (Id),
Name nvarchar not null
);
create table dbo.PostsLocalized_Tags
(
PostLocalizedId int not null,
TagId int not null,
constraint PK_PostsLocalized_Tags_Post_PostLocalizedId_TagId primary key clustered (PostLocalizedId, TagId)
);
Then I have added the following constraints:
alter table dbo.PostsLocalized
add constraint FK_PostsLocalized_Id foreign key (Id) references dbo.Posts(Id) on delete cascade on update cascade;
alter table dbo.PostsLocalized_Tags
add constraint FK_PostsLocalized_Tags_PostLocalizedId foreign key (PostLocalizedId) references PostsLocalized(Id) on delete cascade on update cascade,
constraint FK_PostsLocalized_Tags_TagId foreign key (TagId) references Tags(Id) on delete cascade on update cascade;
But I get the following error:
There are no primary or candidate keys in the referenced table 'PostsLocalized' that match the referencing column list in the foreign key 'FK_PostsLocalized_Tags_PostLocalizedId'.
How can I solve this?
Thank You,
Miguel
SQL Server mandates that foreign key references be to a primary key or unique key. The foreign key reference has to be to all the columns that constitute the primary/unique key. The documentation says:
In a foreign key reference, a link is created between two tables when
the column or columns that hold the primary key value for one table
are referenced by the column or columns in another table. This column
becomes a foreign key in the second table.
A FOREIGN KEY constraint does not have to be linked only to a PRIMARY
KEY constraint in another table; it can also be defined to reference
the columns of a UNIQUE constraint in another table. A FOREIGN KEY
constraint can contain null values; however, if any column of a
composite FOREIGN KEY constraint contains null values, verification of
all values that make up the FOREIGN KEY constraint is skipped. To make
sure that all values of a composite FOREIGN KEY constraint are
verified, specify NOT NULL on all the participating columns.
The primary key in PostsLocalized contains the culture column, so you need to add it into the foreign key reference.
Your PK on PostsLocalized table is complex consisting of two columns - id and culture and you are trying to create FK on only one of those columns which is not possible.
You'll have to either add Culture column on PostsLocalized_Tags and use them both in foreign key or remove Culture from your PK on PostLocalized