error creating foreign key on categoryid check data types
here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this site About Us Learn more about Stack Overflow the company Business Learn more about hiring error creating foreign key on name (check data types) developers or posting ads with us Stack Overflow Questions Jobs Documentation Tags Users Badges Ask error creating foreign key on table (check data types) Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 4.7 million programmers, just like you, helping each other. Join #1452 - cannot add or update a child row: a foreign key constraint fails them; it only takes a minute: Sign up Foreign Key Constrain Fails with “Error creating foreign key on [table] (check data types)” up vote 4 down vote favorite The following query fails with error "Error creating foreign key on city (check data types)": ALTER TABLE `hotels` ADD FOREIGN KEY ( `city` ) REFERENCES `mydatabase`.`cities` (`id`) ON DELETE CASCADE ON UPDATE CASCADE ; Basically I want to have a ony-to-many relation between city.id and hotels.city. Here are both tables: CREATE TABLE IF NOT EXISTS `cities` ( `id` int(11) NOT NULL AUTO_INCREMENT, PRIMARY KEY (`id`) ) ENGINE=InnoDB; CREATE TABLE IF NOT EXISTS `hotels` ( `id` int(11) NOT NULL AUTO_INCREMENT, `city` bigint(20) DEFAULT NULL, PRIMARY KEY (`id`), KEY `city` (`city`) ) ENGINE=InnoDB; mysql share|improve this question edited Aug 12 '12 at 22:29 asked Aug 12 '12 at 22:23 hasMobi - Android Apps 3,15943373 Do the tables already have data in them? –Tieson T. Aug 12 '12 at 22:25 Hotels is empty, City has some rows that are already constrained with another table (restaurants) in the same way I am trying for hotels above. It worked the first time, but I built the query by hand, without using phpMyAdmin. –hasMobi - Android Apps Aug 12 '12 at 22:26 One is INT, the other BIGINT. –ypercubeᵀᴹ Aug 12 '12 at 22:26 Did you read the error message? It contains the info to solve the problem. –Pred Oct 22 '15 at 9:37 add a comment| 3 Answers 3 active oldest votes up vote 14 down vote accepted The data types need to match: cities.id int(11) hotels.city bigint(20) Needs to become either: cities.id bigint(20) hotels.city bigint(20) Or: cities.id int(11) hotels.city int(11) Depending on what your application needs. Also worth mentioning is the fact that both need to be either signed or unsigned. You may need to OPTIMIZE your tables after changing the data types to match. share|improve this answer edited Jul 3 at 14:18 alexw 2,0971926 answered Aug 12 '12 at 22:26 Mihai Stancu 11.2k11638 Right. I have mistakenly changed the data type of hotels.id to match cities.id without r
Simple Database Design Errors You Should Avoid 16 October 2009Five Simple Database Design Errors You Should AvoidAnith follows up his highly successful article Facts and Fallacies about First Normal Form with a fascinating discussion of five common database design errors which persist in spite of the fact that the unfortunate consequences of their use is so widely known. It is a needy reminder to anyone who has to design databases. 240 22 Anith Sen Most of us in the industry are aware of the dangers of poor database design yet overlook them in real-world databases. Harmful design flaws often go unnoticed. In some cases, the limitations of the DBMS or the SQL language itself may contribute to the problem. In others, it http://stackoverflow.com/questions/11926324/foreign-key-constrain-fails-with-error-creating-foreign-key-on-table-check-d may be the inexperienced database designers who pay more attention to writing fanciful code but fail to focus on having a good data model. To put it simply, database design is the process of translating facts about part of the real world into a logical model. This model can then be implemented, and is usually done so with a relational database. While it is true that relational databases have the solid foundation of logic and set-based mathematics, the scientific rigor of the https://www.simple-talk.com/sql/database-administration/five-simple-database-design-errors-you-should-avoid/ database design process also involves aesthetics and intuition; but it includes, of course, the subjective bias of the designer as well. But how far does this affect the design? In this article, I'll try to explain five common design errors people make while modelling tables and suggest some guidelines on how to avoid them. (1) Common Lookup Tables Figure 1 A few years back, Don Peterson wrote an article for SQL Server Central that detailed a common practice of creating a single lookup table for various types of data usually called as code table or an "allowed value table" (AVT). These tables tend to be massive and have a pile of unrelated data. Appropriately enough, Don called these tables Massively Unified Code-Key (MUCK) tables (Peterson, 2006) Though many others have written about it over the years, this name seems to capture most effectively the clumsiness associated with such a structure. In many cases, the data in these tables are VARCHAR(n) though the real data type of these values can be anything ranging from INTEGER to DATETIME. They are mostly represented in three columns that may take some form of the sample table (Figure 1): The justification here is that each entity in the example here has a similar set of attributes and therefore it is okay to cram it to a single table. After all, it results in fewer tables, keep the database simpler, right? During the design process, the databa
von GoogleAnmeldenAusgeblendete FelderBooksbooks.google.de - Marketshare for DB2 has been growing steadily over the past 5 years and with the https://books.google.com/books?id=YiO2oUNtXLQC&pg=PA223&lpg=PA223&dq=error+creating+foreign+key+on+categoryid+check+data+types&source=bl&ots=nxgh-ou88v&sig=vKKAbNyZO3J3gCt61yt3uegjxmA&hl=en&sa=X&ved=0ahUKEwi0nvfsv8rPAhV recent release of DB2 Universal Database V8, the product has never had more momentum. Not only is the product used in http://zumero.com/docs/zumero_for_sql_server_manager.html every company on the Fortune 500, but it is becoming very popular in the small to medium sized businesses...https://books.google.de/books/about/Sams_Teach_Yourself_DB2_Universal_Databa.html?hl=de&id=YiO2oUNtXLQC&utm_source=gb-gplus-shareSams Teach Yourself DB2 foreign key Universal Database in 21 DaysMeine BücherHilfeErweiterte BuchsucheDruckversionKein E-Book verfügbarSams PublishingAmazon.deBuch.deBuchkatalog.deLibri.deWeltbild.deIn Bücherei suchenAlle Händler»Stöbere bei Google Play nach Büchern.Stöbere im größten eBookstore der Welt und lies noch heute im Web, auf deinem Tablet, Telefon oder E-Reader.Weiter zu Google Play »Sams Teach Yourself DB2 Universal error creating foreign Database in 21 DaysSusan M. Visser, Bill WongSams Publishing, 2003 - 601 Seiten 2 Rezensionenhttps://books.google.de/books/about/Sams_Teach_Yourself_DB2_Universal_Databa.html?hl=de&id=YiO2oUNtXLQCMarketshare for DB2 has been growing steadily over the past 5 years and with the recent release of DB2 Universal Database V8, the product has never had more momentum. Not only is the product used in every company on the Fortune 500, but it is becoming very popular in the small to medium sized businesses as well.Sams Teach Yourself DB2 Universal Database in 21 Days, Second Edition, focuses on performing tasks using the graphical interfaces and wizards that are provided with DB2 on the Windows platform. (DB2 also runs on z/OS, OS/400, AIX, Linux, HP-UX, and Sun Solaris.) Readers are guided through performing all the commonly used tasks to run DB2, including insta
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