I have a web app that calls an sql script that is trying to delete a row from table_1. However, table_2 references it with an FK constraint, so this was giving an error. I manually deleted the referencing row of table_2. (I confirmed via query that it's gone.) Then I ran the app and I still get the same error! (The DELETE statement conflicted with the REFERENCE constraint "table_2_fk". The conflict occurred in database "my_db", table "table_2", column 'table_1_pk'.
Why?
Table info
table_2 has columns pk, name, and table_1_pk. It has an FK constraint table_2_fk that ensures that table_1_fk = table_1.pk
table_1 has pk, a bunch of other columns, and no FK constraint.
details of delete and query
Suppose that table_1.pk = 1. I ran the statement
delete from table_2 where table_1_pk = 1
I then queried the db:
select * from table_2 where table_1_pk = 1
This returned 0 results.
You should change your code so that you delete from table 2 first, then delete from table 1. Or optionally add a Cascade delete to you foreign key constraint (automatically deletes from table 2 when a delete is made in table 1)
ADD CONSTRAINT [FK_Table2_table1] FOREIGN KEY([table_1_pk])
REFERENCES [dbo].[table1] ([table_1_fk ])
ON DELETE CASCADE
Related
I have table on which I have a foreign key constraint like below
ALTER TABLE [dbo].[Element] WITH CHECK
ADD CONSTRAINT [FK_Element_Band]
FOREIGN KEY([BandID]) REFERENCES [dbo].[Band] ([BandID])
GO
ALTER TABLE [dbo].[Element] CHECK CONSTRAINT [FK_Element_Band]
GO
Now I am trying to delete a row from the band table like this
DELETE FROM Band
WHERE TypeID = 21 AND BandUpperLimit = 10000 AND PID = 61
But I am getting a reference constraint error:
The DELETE statement conflicted with the REFERENCE constraint "FK_Element_Band". The conflict occurred in database "pricingModified", table "dbo.Element", column 'BandID'.
So this should happen if I have anything in the Elements table which is referencing Band table with the ID 21 but that's not the case since the SQL
SELECT *
FROM Element
WHERE BandID = 21
returns nothing.
Can someone please tell me why I am not able to delete row data from the parent table even though there is no reference present in the child table?
Thanks
Just specify ON DELETE CASCADE in your foreign key constraint. Then when you delete a row from the Band table it will automatically delete any child records in the Element table.
ALTER TABLE [dbo].[Element] WITH CHECK
ADD CONSTRAINT [FK_Element_Band]
FOREIGN KEY([BandID]) REFERENCES [dbo].[Band] ([BandID]) ON DELETE CASCADE
GO
Check with this query instead:
select b.*
from Element e
inner join Band b
on e.BandId = b.BandId
where b.TypeId = 21
and b.BandUpperLimit = 10000
and b.PID = 61
while creating child table
create table <child_table_name>
(
_______,
_______,
([FOREIGN KEY column_name]) [size of FOREIGN KEY column] references [parent table(primary key column_name)] on delete cascade
)
Using this you can easily delete record of fk using delete operation..
Try this, if it is successful then mark it positive...
how can this statement:
DELETE FROM passage
WHERE passageid NOT IN
(
SELECT passageid from PreEndedPassages_passages
UNION SELECT fromPassageid from severalvisit
UNION SELECT toPassageid from severalvisit
UNION SELECT registerPassageid from stationobjects WHERE registerpassageid IS NOT NULL
UNION SELECT beginPassageid from stationobjects WHERE beginPassageid IS NOT NULL
UNION SELECT endPassageid from stationobjects WHERE endPassageid IS NOT NULL
)
throw this exception?
The DELETE statement conflicted with the FOREIGN KEY constraint "FK_statobj_begpasid". The conflict occurred in database "db.mdf", table "dbo.stationobjects", column 'beginpassageid'.
I have no clue, but it happened. beginPassageId is a foreign key on passageid.
EDIT:
Consider the NOT IN. I want to delete all passages that don't exist in one of its related tables. It usually works, but it happened once.
Thank you.
It means passage is parent table. and stationobjects is child table. You are trying to remove passageid from passage table which is present in stationobjects table as well.
First try to remove those passageid from stationobjects and then you can run this delete statement.
Alternate approach is cascade delete, if your DB supports that.
this kind of occur when you have a foreign key relationship in the two table.
This violates the Refrential Integrity .
so if you delete record from the primary table and record exist in foreign key table,
then you have two options:
1. either set the delete rule to cascade so that when ever you delete primary record the foreign key table record will get automatically deleted.
2.delete record from foreign key table first then from primary key table.
These kind of errors come up when table A foreign key is table B primary key and when you try to delete record in table A that has linking in table B, then deletion will not happen. Try dropping foreign key relation before delete. Same way truncate is used in tables by dropping fk relations and rebuilding them again after the table is reset
I have a stored procedure that deletes a record from a table where one of the columns matches a specified value:
ALTER PROCEDURE [dbo].[Sp_DelBranch] #datafield varchar(50)
AS
BEGIN
DELETE FROM Branch WHERE branchname = #datafield
END
Unfortunately I get the following error on execution:
The DELETE statement conflicted with the REFERENCE constraint "fk_BranchIdDept". The conflict occurred in database "MproWorkSpace", table "dbo.Department", column 'BranchId'.
Can anyone explain why I'm seeing this error?
conflicted with the REFERENCE constraint "fk_BranchIdDept".
This means, that the value you are trying to delete, is primary key in some other table and is referenced in this table as foreign key,i.e., a primary-foreign key relation is mapped through constraint fk_BranchIdDept ...So unless you delete the referred primary key, foreign key can not be removed from table.
Otherwise, this will lead to data inconsistency!
Look for Cascade Delete to help you in this!
SQL ON DELETE CASCADE, Which Way Does the Deletion Occur?
The DELETE statement conflicted with the REFERENCE constraint "fk_BranchIdDept".
The record you're trying to delete is referenced in other tables; deleting the Branch record would leave the other tables orphaned, and referencing something that no longer exists.
There are two approaches to this:
Delete all records in referenced tables before deleting from the Branch table
Perform a cascade delete (deleting from the Branch table triggers a delete in every referenced table)
The error means that there are some rows in Department table referencing the branch you're trying to delete.
You should either delete the corresponding rows from the Department table first, or change values in BranchId column for these rows, so they point to some other branch.
Consider we have two tables ProductType and ProductSizeGroup as below
ProductType
Id
Name
MaleSizeGroupId
FemaleSizeGroupId
ChildSizeGroupId
ProductSizeGroup
Id
Name
Each of MaleSizeGroupId, FemaleSizeGroupId and ChildSizeGroupId fields should be FKs to ProductSizeGroup.Id.
I add one using the following statement:
ALTER TABLE [dbo].[ProductType]
WITH CHECK ADD CONSTRAINT
[FK_ProductType_ProductSizeGroup_Male] FOREIGN KEY([MaleGroupId])
REFERENCES [dbo].[ProductSizeGroup] ([Id])
This works fine. I try to add the next using
ALTER TABLE [dbo].[ProductType]
WITH CHECK ADD CONSTRAINT
[FK_ProductType_ProductSizeGroup_Female] FOREIGN KEY([FemaleGroupId])
REFERENCES [dbo].[ProductSizeGroup] ([Id])
But I get the error:
The ALTER TABLE statement conflicted with the FOREIGN KEY constraint "FK_ProductType_ProductSizeGroup_Female". The conflict
occurred in database "dbname", table "dbo.ProductSizeGroup", column
'Id'.
So there is conflict.. but what conflict? What should I be looking for?
That just means: there are rows in your table ProductType that have values in the FemaleGroupId column which do not exist in the referenced table (ProductSizeGroup).
It's not a problem per se - you can totally have multiple columns going from one table to another.
The problem is with the existing data - you have data in there that doesn't live up to that FK constraint. Fix that data and you should be fine.
To find those offending rows, use a query like this:
SELECT *
FROM [dbo].[ProductType]
WHERE FemaleGroupId NOT IN (SELECT DISTINCT Id FROM [dbo].[ProductSizeGroup])
That will list all offending rows - update their attribute and get going again!
Create Trigger:
SELECT #oldVersionId = (SELECT DISTINCT VERSION_ID FROM Deleted)
SELECT #newVersionId = (SELECT DISTINCT VERSION_ID FROM Inserted)
SELECT #appId = (SELECT DISTINCT APP_ID FROM Deleted)
UPDATE [TableName]
SET [VERSION_ID] = #newVersionId
WHERE (([VERSION_ID] = #oldVersionId) AND ([APP_ID] = #appId) )
Can this Trigger be replace with a Foreign Key to update the VERSION_ID ?
What I think could be a problem is the AND condition, how to express that in a FK with On del/update Cascade?
FOREIGN KEY CONSTRAINTS don't update anything. They check the values being written to a record and cause the write to fail if they cause a constraint to fail.
Also, as #marc_s points out in his comment, triggers in MS SQL Server are set based. The INSERTED and DELETED tables can hold multiple records at once. Your code only works for one record.
You could try something along these lines...
UPDATE
table
SET
VERSION_ID = inserted.VERSION_ID
FROM
table
INNER JOIN
deleted
ON table.VERSION_ID = deleted.VERSION_ID
AND table.APP_ID = deleted.APP_ID
INNER JOIN
inserted
ON deleted.PRIMARY_KEY = inserted.PRIMARY_KEY
EDIT
I just read your comment, and I think I understand. You want a foreign key constraint with ON UPDATE CASCADE.
You use this format to create that with DDL.
ALTER TABLE DBO.<child table>
ADD CONSTRAINT <foreign key name> FOREIGN KEY <child column>
REFERENCES DBO.<parent table>(<parent column>)
{ON [DELETE|UPDATE] CASCADE}
Or you could just SQL Server Management Studio to set it up. Just make sure the ON UPDATE CASCADE is present.
I cannot really tell you what you're looking for - you're too unclear in your question.
But basically, if two tables are linked via a foreign key constraint, of course you can add a clause to that to make sure the child table gets updated when the parents table's PK changes:
ALTER TABLE dbo.ChildTable
ADD CONSTRAINT FK_ChildTable_ParentTable
FOREIGN KEY(ChildTableColumn) REFERENCES dbo.ParentTable(PKColumn)
ON UPDATE CASCADE
The ON UPDATE CASCADE does exactly that - if the referenced column (the PKColumn in ParentTable) changes, then the FK constraint will "cascade" that update down into the child table and update it's ChildTableColumn to match the new PKColumn
Read all about cascading referential integrity constraints and what options you have on MSDN Books Online