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Performance on dozens of inserts at the time is the key factor (using PHP).This is a routine that may be called inside other transactions so avoiding transactions would be preferable. In worst case I can do transactions if they are performant enough when compared to other solutions.Comfortable way would be trigger after insert on aliases that inserts a row into meanings and updates back inserted row's aningId but I am worried about performance.Records are permanent and will never be removed.Optimize for mass insert of average of ~40 aliases at the time.Account for many processes doing the same thing simultaneously.The SQL table scheme is given as above (although new cols can be added).SELECT IF(row_count() > 0, last_insert_id(), 0) INTO INTO meanings (id) SELECT null FROM aliases WHERE IFNULL(last_insert_id(), 0) INTO aliases SET WHERE constraints/conditions/wishes: In a nutshell I need to do following but faster: INSERT IGNORE INTO aliases (phrase, meaningId) VALUES ('word1', NULL)
SET FOREIGN KEY RAZORSQL UPDATE
`meaningId` int(10) unsigned DEFAULT NULL,ĬONSTRAINT `fk_Synonyms_1` FOREIGN KEY (`meaningId`) REFERENCES `meanings` (`id`) ON DELETE CASCADE ON UPDATE CASCADE `id` int(10) unsigned NOT NULL AUTO_INCREMENT, In that case none of the rows should be inserted. Caveat: The insert into dependable table may fail due to duplicate key conflict. I have two MySQL tables and I need to insert a record in each of them. What is the proper way to alter a model field into a foreign key that points to an existing table that contains some data. Have a corresponding value in blog_category.id. Table 'blog_article' with primary key '1' has an invalid foreign key:īlog_article.category_id contains a value 'Calculus' that does not Raise IntegrityError( django.db.utils.IntegrityError: The row in I tried to deleted category field's default value: category = models.ForeignKey(Category, on_delete=models.SET_NULL, So, Django doesn't find any category object to point existing articles to. If a category object gets deleted, the category field of articles pointing to it should become null.
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# category = models.CharField(max_length=50)Ĭategory = models.ForeignKey(Category, on_delete=models.SET_NULL,ĭefault=(title=title)) The category table is created as follows and those fields are changed to foreign keys: # I want to change the category field to foreign key. And, the category field of them is not empty: # Ĭategory = models.CharField(max_length=50) Select * from SYSFOREIGNKEYS where primary_tname='table_name' There is no relationship between actual/enforced RI constraints (created via the create table/ alter table commands) and 'documented' RI constraints (created via sp_fkeys/ sp_pkeys invocations).
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The accuracy of the results from running sp_fkeys/ sp_keys is dependent on whether or not the dbo/table owner remembers to 'document' these RI constraints. Sp_fkeys/ sp_pkeys were used to 'document' these trigger-based RIĬonstraints so that 3rd party apps had a means of querying the Triggers had to be used to enforce RI requirements and therefore. The sp_fkeys/ sp_pkeys procs are a throwback to earlier times when:ĪSE did not have table-level RI constraints so. Sp_helpconstraint will display all primary, unique, foreign key and check constraints on a table. If by 'foreign key' you're referring to referential integrity (RI) foreign key constraints, try: exec sp_helpconstraint
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It will reject any INSERT or UPDATE operation that attempts to create a foreign key value in a child table if there is no a matching candidate key value in the parent table.NOTE: I'm assuming you're using the (Sybase) ASE product. The FOREIGN KEY clause is specified in the child table. “Foreign key relationships involve a parent table that holds the central data values, and a child table with identical values pointing back to its parent. The error comes when you are trying to add a row for which no matching row in in the other table. Mysql> insert into ChildDemo values(1,3) ĮRROR 1452 (23000): Cannot add or update a child row: a foreign key constraint fails (`business`.`childdemo`, CONSTRAINT `ConstChild` FOREIGN KEY (`FKPK`) REFERENCES `parentdemo` (`fkpk`)) Mysql> alter table ChildDemo add constraint ConstChild foreign key(FKPK) references ParentDemo(FKPK) Īfter creating foreign key constraint, whenever we insert records into the first table or child table, we will get the above error. This error comes whenever we add a foreign key constraint between tables and insert records into the child table.