Foreign Key Error
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Foreign Key Mismatch - Referencing
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Sqlite Foreign Key
a community of 4.7 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign up What is causing Foreign Key Mismatch error? up vote 5 down vote favorite 1 sqlite foreign key constraint failed I have an sqlite database structured as follows: CREATE TABLE IF NOT EXISTS Patient ( PatientId INTEGER PRIMARY KEY AUTOINCREMENT ); CREATE TABLE IF NOT EXISTS Event ( PatientId INTEGER REFERENCES Patient( PatientId ), DateTime TEXT, EventTypeCode TEXT, PRIMARY KEY( PatientId, DateTime, EventTypeCode ) ); CREATE TABLE IF NOT EXISTS Reading ( PatientId INTEGER REFERENCES Patient( PatientId ), DateTime TEXT REFERENCES Event (DateTime), EventTypeCode TEXT REFERENCES Event (EventTypeCode), Value REAL, foreign key constraint fails PRIMARY KEY( PatientId, DateTime, EventTypeCode ) ); I insert a Patient with Id #1 then I run: INSERT INTO Event (PatientId, DateTime, EventTypeCode) VALUES (1, '2011-01-23 19:26:59', 'R') which works then I run: INSERT INTO Reading (PatientId, DateTime, EventTypeCode, Value) VALUES (1, '2011-01-23 19:26:59', 'R', 7.9) and it gives me a foreign key mismatch. Patient Id is '1' in all cases, and the datetime and typecodes match in the 2nd and 3rd queries. I do not understand what is mismatching, but I'm a bit new to actually defining foreign keys and i do not know what I am doing wrong. sql sqlite foreign-keys constraints share|improve this question asked Mar 6 '11 at 2:29 Damon 3,2411050101 Can you cite the message in complete please? –user unknown Mar 6 '11 at 2:50 "error : foreign key mismatch" haha.. doesn't add too much does it. I was hoping for something a little more specific, too. –Damon Mar 6 '11 at 2:53 add a comment| 1 Answer 1 active oldest votes up vote 24 down vote accepted I'm not familiar with SQLite but a little Google'ing turned up this. The documentation says If the database schema contains foreign key errors that require looking at more than one table definition
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Cannot Add Or Update A Child Row: A Foreign Key Constraint Fails
Badges Ask 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 them; it only takes http://stackoverflow.com/questions/5208245/what-is-causing-foreign-key-mismatch-error a minute: Sign up SQL Server : add foreign key error up vote 1 down vote favorite I have a Microsoft SQL Server database of about 8 tables that I am trying to update. I create temporary tables, drop the existing tables, rename the temporary tables to their final names, then create indexes and foreign key constraints to speed up look http://stackoverflow.com/questions/30131652/sql-server-add-foreign-key-error ups. The problem is when I try to create the foreign key constraints on the renamed tables I receive the following error. The ALTER TABLE statement conflicted with the FOREIGN KEY constraint "FK__maintenance_interval_id". The conflict occurred in database "vehicle_data", table "MAINTENANCE_INTERVAL", column 'maintenance_interval_id'. Here is the statement that is causing the problem ALTER TABLE VEH_ENG_MAINTENANCE_INTERVAL ADD CONSTRAINT FK_maintenance_interval_id FOREIGN KEY (maintenance_interval_id) REFERENCES MAINTENANCE_INTERVAL(maintenance_interval_id) People have pointed out that it is likely caused by a mismatch of data in the columns of each table. Is there an easy way to check this? Both tables have thousands of entries. Create table statement : CREATE TABLE [vehicle_data].[dbo].[MAINTENANCE_INTERVAL] [maintenance_interval_id] int, [interval_type] varchar(32), [value] decimal(18,2), [units] varchar(32), [initial_value] decimal(18,2), PRIMARY KEY CLUSTERED ([maintenance_interval_id] ASC)) sql sql-server sql-server-2012 foreign-keys foreign-key-relationship share|improve this question edited May 8 '15 at 20:27 asked May 8 '15 at 19:39 nastassiar 5101928 You're trying to add a foreign key, but the data in the tables doesn't play by the rules - obviously, you have data in VEH_ENG_MAINTENANCE_INTERVAL that has a value in maintenance_interval_id that doesn't exist as a value in MAINTENANCE_INTERVA
Connectors More MySQL.com Downloads Developer Zone Section Menu: Documentation Home MySQL 5.7 Reference Manual Preface and http://dev.mysql.com/doc/en/innodb-foreign-key-constraints.html Legal Notices General Information Installing and Upgrading MySQL Using https://mariadb.org/mariadb-innodb-foreign-key-constraint-errors/ MySQL as a Document Store Tutorial MySQL Programs MySQL Server Administration Security Backup and Recovery Optimization Language Structure Globalization Data Types Functions and Operators SQL Statement Syntax The InnoDB Storage Engine Introduction to InnoDB Benefits of Using foreign key InnoDB Tables Best Practices for InnoDB Tables Checking InnoDB Availability Testing and Benchmarking with InnoDB Turning Off InnoDB InnoDB and the ACID Model InnoDB Multi-Versioning InnoDB Architecture Buffer Pool Change Buffer Adaptive Hash Index Redo Log Buffer System Tablespace InnoDB Data Dictionary Doublewrite Buffer Undo Log File-Per-Table foreign key constraint Tablespaces General Tablespaces Undo Tablespace Temporary Tablespace InnoDB Temporary Table Undo Logs Redo Log Group Commit for Redo Log Flushing InnoDB Locking and Transaction Model InnoDB Locking InnoDB Transaction Model Transaction Isolation Levels autocommit, Commit, and Rollback Consistent Nonlocking Reads Locking Reads Locks Set by Different SQL Statements in InnoDB Phantom Rows Deadlocks in InnoDB An InnoDB Deadlock Example Deadlock Detection and Rollback How to Minimize and Handle Deadlocks InnoDB Configuration InnoDB Startup Configuration Configuring InnoDB for Read-Only Operation InnoDB Buffer Pool Configuration The InnoDB Buffer Pool Configuring InnoDB Buffer Pool Size Configuring Multiple Buffer Pool Instances Making the Buffer Pool Scan Resistant Configuring InnoDB Buffer Pool Prefetching (Read-Ahead) Configuring InnoDB Buffer Pool Flushing Fine-tuning InnoDB Buffer Pool Flushing Saving and Restoring the Buffer Pool State Monitoring the Buffer Pool Using the InnoDB Standard Monitor Configuring the Memory Allo
for Developers MariaDB Contributor Agreement MariaDB Contributor Agreement FAQs Community Ambassadors Events Past Events and Conferences Sponsor Sponsors List of Donors Blog About MariaDB Sponsors Governance Logos and Badges MariaDB Trademark Usage Statistics Service Providers Maintenance Policy Security Policy Download Learn Get Involved Social Media Getting Started for Developers MariaDB Contributor Agreement MariaDB Contributor Agreement FAQs Community Ambassadors Events Past Events and Conferences Sponsor Sponsors List of Donors Blog HomeGeneralMariaDB: InnoDB foreign key constraint errors MariaDB: InnoDB foreign key constraint errors 2015-08-07 4 Comments Written by Jan Lindstrom Introduction A foreign key is a field (or collection of fields) in one table that uniquely identifies a row of another table. The table containing the foreign key is called the child table, and the table containing the candidate key is called the referenced or parent table. The purpose of the foreign key is to identify a particular row of the referenced table. Therefore, it is required that the foreign key is equal to the candidate key in some row of the primary table, or else have no value (the NULL value). This is called a referential integrity constraint between the two tables. Because violations of these constraints can be the source of many database problems, most database management systems provide mechanisms to ensure that every non-null foreign key corresponds to a row of the referenced table. Consider following simple example: create table parent ( id int not null primary key, name char(80) ) engine=innodb; create table child ( id int not null, name char(80), parent_id int, foreign key(parent_id) references parent(id) ) engine=innodb; As far as I know, the following storage engines for MariaDB and/or MySQL support foreign keys: InnoDB (both innodb_plugin and XtraDB) PBXT (https://mariadb.com/kb/en/mariadb/about-pbxt/) SolidDB for MySQL (http://sourceforge.net/projects/soliddb/) ScaleDB (https://mariadb.com/kb/en/mariadb/scaledb/ and http://scaledb.com/pdfs/TechnicalOverview.pdf) MySQL Cluster NDB 7.3 or later (https://dev.mysql.com/doc/refman/5.6/en/mysql-cluster-ndb-innodb-engines.html) MariaDB foreign key syntax is documented at https://mariadb.com/kb/en/mariadb/foreign-keys/ (and MySQL at http://dev.mysql.com/doc/refman/5.5/en/