I am trying to migrate a table which has 2 colums.
Id - Primarky key
Parent ID - Foreign key populated by the value above (Id).
(So basically the FK is in the same table)
When I migrate this, I get the following error.
"The UPDATE statement conflicted with the FOREIGN KEY SAME TABLE constraint"
Please let me know how to deal with this.
Thanks in advance
Disable the foreign key constraint first. Then migrate your data. And afterwards you can enable the constraint again.
ALTER TABLE Purchasing.PurchaseOrderHeader
NOCHECK CONSTRAINT FK_PurchaseOrderHeader_Employee_EmployeeID;
ALTER TABLE Purchasing.PurchaseOrderHeader
CHECK CONSTRAINT FK_PurchaseOrderHeader_Employee_EmployeeID;
Disable foreign key constraints with INSERT and UPDATE statements
Use Case:
I am performing performance execution on an database and I am trying to do following:
I took an backup of the database (the mdf and ldf file) at the early stage (lets called a "baselinecopy").
After that I execute some performance script .And the database reach to baselinecopy+Additional_Row (let it be "NewDatabase") from the test.
Then I replace the database baselinecopy with NewDatabase & start the server. While trying to perform operation on application it is giving me Violation of PRIMARY KEY constraint to test_order. Cannot insert duplicate key in object.
I check the "IDENTITY" but the table has no identity set.
Any thoughts on this ?
Violation of PRIMARY KEY constraint to test_order. Cannot insert duplicate key in object.
This is exactly what it says.
You have defined a primary key on a table and are attempting to insert a record that contains the same primary key as an existing record.
It does not need to be an identity column to be a primary key column.
I love foreign keys, but I'm running into one problem with them. I have a conversion program where I am disabling foreign keys to tables. The reason I'm doing this is so that I can reconvert all records in the main table, but leave the other tables dependent on that one untouched without having to reconvert them every time because they are HUGE.
I'm using these commands to disable and re-enable the foreign keys:
ALTER TABLE MyTable NOCHECK CONSTRAINT MyConstraint
ALTER TABLE MyTable CHECK CONSTRAINT MyConstraint
However, after I re-enable the constraint "Check Existing Data on Creation or Re-Enabling" is still set to No. I understand that it is set to No because I disabled the constraint, but by doing this it altered my database schema, which I don't like. I thought this would be considered re-enabling the constraint and would check the existing data, but apparently not.
Is there no way to change this with the ALTER TABLE command? I know I can if I drop the constraint and recreate it, but I'm not about to write the script to recreate every foreign key I have and maintain that.
I'm using SQL Server 2008 R2.
To re-enable a constraint:
-- Enable the constraint
ALTER TABLE MyTable
WITH CHECK CHECK CONSTRAINT MyConstraint
GO
Note: you have to specify CHECK twice to force a check that all foreign key values are valid.
FOREIGN KEY and CHECK constraints that are disabled are marked
is_not_trusted.These are viewable in the sys.check_constraints and
sys.foreign_keys catalog views. This means that the constraint is no
longer being verified by the system for all rows of the table. Even
when you re-enable the constraint, it will not reverify the existing
rows against the table unless you specify the WITH CHECK option of
ALTER TABLE. Specifying WITH CHECK marks the constraint as trusted
again.
Ref.: Guidelines for Disabling Indexes and Constraints
As noted in comments (for search engines), this corresponds to
sys.foreign_keys.is_not_trusted
in the catalog view
I have a row in a table. This row has an ID column referenced in a few other tables with millions of rows. The SQL statement to delete the row always times out. From my design, I know the row I wish to delete is never referenced any where else. Hence I would like SQL to ignore having to check all other tables for a foreign key reference to this row and delete the row immediately. Is there a quick way to do this in SQL 2008?
Perhaps something along the lines of:
DELETE FROM myTable where myTable.ID = 6850 IGNORE CONSTRAINTS
Or something along those lines.
You can set the constraints on that table / column to not check temporarily, then re-enable the constraints. General form would be:
ALTER TABLE TableName NOCHECK CONSTRAINT ConstraintName
Then re-enable all constraints with
ALTER TABLE TableName CHECK CONSTRAINT ConstraintName
I assume that this would be temporary though? You obviously wouldn't want to do this consistently.
Yes, simply run
DELETE FROM myTable where myTable.ID = 6850
AND LET ENGINE VERIFY THE CONSTRAINTS.
If you're trying to be 'clever' and disable constraints, you'll pay a huge price: enabling back the constraints has to verify every row instead of the one you just deleted. There are internal flags SQL keeps to know that a constraint is 'trusted' or not. You're 'optimization' would result in either changing these flags to 'false' (meaning SQL no longer trusts the constraints) or it has to re-verify them from scratch.
See Guidelines for Disabling Indexes and Constraints and Non-trusted constraints and performance.
Unless you did some solid measurements that demonstrated that the constraint verification of the DELETE operation are a performance bottleneck, let the engine do its work.
Do not under any circumstances disable the constraints. This is an extremely stupid practice. You cannot maintain data integrity if you do things like this. Data integrity is the first consideration of a database because without it, you have nothing.
The correct method is to delete from the child tables before trying to delete the parent record. You are probably timing out because you have set up cascading deltes which is another bad practice in a large database.
I know this is an old thread, but I landed here when my row deletes were blocked by foreign key constraints. In my case, my table design permitted "NULL" values in the constrained column. In the rows to be deleted, I changed the constrained column value to "NULL" (which does not violate the Foreign Key Constraint) and then deleted all the rows.
I wanted to delete all records from both tables because it was all test data. I used SSMS GUI to temporarily disable a FK constraint, then I ran a DELETE query on both tables, and finally I re-enabled the FK constraint.
To disable the FK constraint:
expand the database object [1]
expand the dependant table object [2]
expand the 'Keys' folder
right click on the foreign key
choose the 'Modify' option
change the 'Enforce Foreign Key Constraint' option to 'No'
close the 'Foreign Key Relationships' window
close the table designer tab
when prompted confirm save changes
run necessary delete queries
re-enable foreign key constraint the same way you just disabled it.
[1] in the 'Object Explorer' pane, can be accessed via the 'View' menu option, or key F8
[2] if you're not sure which table is the dependant one, you can check by right clicking the table in question and selecting the 'View Dependencies' option.
This is the way to disable foreign key checks in MySQL. Not relevant to OP's question since they use MS SQL Server, but google search results do turn this up so here's for reference:
SET FOREIGN_KEY_CHECKS = 0;
/ Run your script /
SET FOREIGN_KEY_CHECKS = 1;
See if this helps, This is for ignoring the foreign key checks.
But deleting disabling this is very bad practice.
On all tables with foreign keys pointing to this one, use:
ALTER TABLE MyOtherTable NOCHECK CONSTRAINT fk_name
You can disable all of the constaints on your database by the following line of code:
EXEC sp_MSforeachtable "ALTER TABLE ? NOCHECK CONSTRAINT all"
and after the runing your update/delete command, you can enable it again as the following:
EXEC sp_MSforeachtable "ALTER TABLE ? WITH CHECK CHECK CONSTRAINT all"
You could maybe disable and re-enable constraints:
http://sqlforums.windowsitpro.com/web/forum/messageview.aspx?catid=60&threadid=48410&enterthread=y
For the testing purpose only, I used the following command in MySQL to delete only one record from a table that has foreign key references.
SET FOREIGN_KEY_CHECKS = 0; -- Disabling foreign key checks before running the following query.
DELETE FROM table_name WHERE id = id_to_delete; -- Deleting a record from a table that has foreign key reference.
SET FOREIGN_KEY_CHECKS = 1; -- Enabling foreign key checks after running the above query.
Temporarily disable constraints on a table T-SQL, SQL Server
MSSQL
ALTER TABLE TableName NOCHECK CONSTRAINT ALL
ALTER TABLE TableName CHECK CONSTRAINT ALL
ALTER TABLE TableName NOCHECK CONSTRAINT FK_Table_RefTable
ALTER TABLE TableName CHECK CONSTRAINT FK_Table_RefTable
ref
DELETE FROM TableName
DBCC CHECKIDENT ('TableName', RESEED, 0)
MySql
SET FOREIGN_KEY_CHECKS = 0; -- Disable foreign key checking.
TRUNCATE TABLE [YOUR TABLE];
SET FOREIGN_KEY_CHECKS = 1;
I need to update the primary key for a record but it's also the foreign key in two other tables. And I need the updated primary key to be reflected in the child tables as well.
Here is my query and the error:
begin tran
update question set questionparent = 10000, questionid= 10005 where questionid = 11000;
Error 9/4/2009 10:04:49 AM 0:00:00.000 SQL Server Database Error: The UPDATE statement conflicted with the REFERENCE constraint "FK_GoalRequirement_Question". The conflict occurred in database "numgmttest", table "dbo.GoalRequirement", column 'QuestionID'. 14 0
I don't remember how to go about doing this so that's why I'm here. Any help?
Are your relationships using
ON UPDATE CASCADE
If they are then changing the key in the primary table will update the foreign keys.
e.g.
ALTER TABLE Books
ADD CONSTRAINT fk_author
FOREIGN KEY (AuthorID)
REFERENCES Authors (AuthorID) ON UPDATE CASCADE
You may:
disable enforcing FK constraints temporarily (see here or here)
update your PK
update your FKs
enable back enforcing FK constraints
do it all within a transaction and make sure that if transaction fails, you roll it back properly and still enforce the FK constraints back.
But... why do you need to change a PK? I hope this is an action that is executed rarely (legacy data import or something like that).
If you would like to set the Cascade rule graphically then Set Cascade Rule on SQL Management Studio
Open table in design mode
Click Relationship button from top toolbar
Select the required FK relations (one by one)
Right Side - Expand INSERT or UPDATE Specification
Change the UPDATE Rule to - Cascade
Close and Save, Done!
(Tried on SQL 2008)
As I'm not too confident disabling FK constraints, I prefer too :
Duplicate the row with the old PK with one with the new PK
Update the FKs
Delete the row with the old PK
Advantage : No constraint violated during the process.
Go to foreign Key Relations of each child tables and on Insert and Update specification change delete and update rules to cascade.
create a New row with the same data and a different primary key.
update all the children tables.
remove the row that you repeated its data
And its done.