A type of integrity constraint used in a RDBMS platform to ensure that a value in a column matches one of a range of key values from another table.

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2
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2answers
111 views

Is there any reason not to use foreign keys in MySQL?

I've never really used foreign keys before but I am building a project where they could come in handy. I have looked at some other large software such as some forum systems and they don't use foreign ...
1
vote
2answers
2k views

VARCHAR primary key - MySQL

Currently, I have a categories table with 2 columns - category VARCHAR(50) NOT NULL PRIMARY KEY and parent VARCHAR(50). The parent column is a foreign key (FK) to the category column. This seems like ...
1
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2answers
130 views

novice-design: Are FOREIGN KEYs always necessary? Joins on columns which are not PK

I've been wondering if following approach is bad or really very bad:). Question#1: can we use indicator_id to combine data from indicator_values and indicator_details tables (without using FOREIGN ...
3
votes
5answers
325 views

How do I prove that the act of removing foreign keys doesn't corrupt existing data?

TL;DR: Prove that in practice, the execution of the alter table table_name drop foreign key constraint_name statement does not corrupt existing data. The important consideration is the execution of ...
4
votes
2answers
533 views

Foreign Keys doesn't work as I expect

Here are my tables; CREATE TABLE `borclular` ( `id` int(11) NOT NULL AUTO_INCREMENT, `tc` char(11) COLLATE utf8_turkish_ci NOT NULL, `borclu` varchar(255) COLLATE utf8_turkish_ci NOT NULL, ...
2
votes
1answer
22 views

Surrogate vs composite key in hierarchical data structure

I'm currently evaluating a schema for a hierarchical data structure. My main problem is how I should design the schema to prevent inconsistent data (reference of foreign key in another hierarchy). The ...
2
votes
1answer
211 views

How to resolve foreign key references across different databases (iSeries and SQL Server)

I've got a system that has a DB2 iSeries database. We are rewriting a portion of the system and implementing it using SQL Server and Entity Framework. Originally, I was lead to believe that there ...
0
votes
1answer
31 views

Phpmyadmin / mysql error defining primary keys as foreign keys of two separate tables

I am designing a mysql database using phpmyadmin 3.3.10.4. Everything in the database is InnoDB. I have two tables, person with primary key person.id_numberand e-mail_address with pk ...
16
votes
2answers
5k views

Why would a table use its primary key as a foreign key to itself

Looking through a database, I came across a table that used its primary key as a foreign key to itself. I've seen that a table can have a foreign key to itself to build a hierarchy structure, but it ...
0
votes
0answers
34 views

Cannot add foreign key constraint'?

Can someone please correct this code for me? When I click enter it says 'cannot add foreign key constraint'? CREATE TABLE entries ( Subject_id smallint auto_increment, Student_id VARCHAR(45) ...
1
vote
4answers
35 views

Foreign and primary keys question

I have have looked for an answer for my questions everywhere but they seem confusing to me.Can a foreign key be a primary key in the same table? Can a foreign key be a primary key in another table? ...
1
vote
1answer
195 views

Sybase ASA: Saving and dropping all foreign keys and most Primary Keys for (Bulk) Insert

Background Information: I am trying to migrate from an ASA 12 Database, to a ASA 12 Database by using a Remote Server. I have to migrate a lot of Rows (not all), spread over a lot of tables (not ...
2
votes
1answer
1k views

How to add FK on a column of composite type in PostgreSQL?

I have a table which contains a composite type and I am trying to connect a column of it to another table's PK. CREATE TABLE aaa (col1 SERIAL PRIMARY KEY); CREATE TYPE bbb AS (col2 INTEGER); CREATE ...
1
vote
2answers
318 views

Multiple relationships between the same entities

Is there a name for when 2 entities can have multiple relationships between them?
4
votes
1answer
532 views

Partialy Solved - Problems Deleting Data

I did a workaround that solved the problem for today but I want to know what I did wrong for the next project. I'm stuck on trying to delete some information on my MySQL database. I've never used a ...
3
votes
1answer
179 views

Table structure for validating data using category and subcategory fields

I am creating a simple budget application, and the primary table will be a transaction table that contains things like the amount of the transaction, date, account, the category and subcategory (the ...
1
vote
1answer
40 views

Why does In-Memory feature not support foreign keys?

Why does Sql-Server 2014 In-Memory feature not support primary/foreign key relations? Can anyone explain what the problem with foreign key relationships and in-memory is? I guess just and only this ...
0
votes
1answer
24 views

Name of ForeignKey Back Relation?

Table detail has a ForeignKey to table master. How to call the back relation? master has ??? to table detail I could not find a canonical word in wikipedia or other resources.
2
votes
1answer
26 views

Replace content of only one table with new version (should disable foreign keys?)

I have 2 tables. 2nd has foreign keys to reference 1st. I need to replace the whole content of the 1st table with the new version from another database. The new version satisfies all constraints and ...
3
votes
0answers
49 views

How does mysql(innoDB) handle same foreign key for join

I have a table called X and another called Y. There is a primary key on Y that is a foreign key on X. Now, my data is such that there will be many rows in X that will have the exact same foreign key ...
1
vote
1answer
33 views

Postgres Can't Add Foreign Key Constraint

I have a table with about 220 million records :( and I need to add a foreign key constraint. My command looks something like this: ALTER TABLE events ADD CONSTRAINT events_visitor_id_fkey FOREIGN ...
0
votes
1answer
31 views

Do Foreign Keys Impose Uniqueness

Do FOREIGN KEYs impose the uniqueness of the the referent? I.e. if I have a foreign key that refers to a UNIQUE constrained column, will the FOREIGN KEY column be unique? I'm particularly wondering ...
1
vote
1answer
80 views

Index cleanup/usage help

My question is this: When running sp_blitzindex, I get a lot of these 2 warnings/suggestions: Index Hoarder: Unused NC index and Feature-Phobic Indexes: Potential filtered index (based on ...
3
votes
2answers
173 views

Database design of Room Booking system in a Hotel

Intro and System Description I am currently designing a Database for a Room Booking system in a Hotel. Client fills a Form / Request with following information about Room: amount of people in room ...
1
vote
2answers
25 views

Recreate all foreign keys in all tables as deferrable (batch)

I want to make all foreign keys in my database deferrable. But there is no possibility to alter an existing constraint. So I need to drop and add again each foreign key. How to do it automatically?
1
vote
1answer
27 views

Cities and States (a few data): single table or splitted?

I am designing a DB schema and I need to store cities and states. I expect only a few rows, let's say, 20 cities. Example: id | city | state 1 | Rio de Janeiro | RJ 2 | Niteroi ...
11
votes
1answer
4k views

MATCH FULL vs MATCH SIMPLE in foreign key constraints

I've noticed a MATCH SIMPLE or MATCH FULL option in phpPgAdmin, but I can't find a description in the docs. The default is MATCH SIMPLE. How do they function?
3
votes
1answer
90 views

Store different rows type in single table

I'd like to create a DB to store different rows type. It will be kind of event list with time stamp. So I'd like to have an Event table with relations to other tables - each table will be a row type ...
0
votes
1answer
14 views

load data infile in mysql server 5.5 can't load data when foreign key exist

I have a database (TPC-DS benchmark base) with 24 tables(17 dimensions tables, 7 facts tables) I generated this database then I created it in mysql server 5.5 I used the instruction load data local ...
1
vote
0answers
36 views

Many-to-many relationship, what's the best choice for primary key? [duplicate]

In advance, I'd like to apologize if it's a duplicate question... I can't find a direct answer, probably because I'm not a native english speaker. Straight to the subject: I have 2 tables: company, ...
3
votes
2answers
403 views

Should I use a compound or surrogate PK in a many-to-many table?

I have a database: DROP TABLE IF EXISTS `books`; CREATE TABLE `books` ( `isbn` VARCHAR(255) NOT NULL, `title` VARCHAR(255) NULL DEFAULT NULL, PRIMARY KEY (`isbn`) ) COMMENT 'Books used at this ...
2
votes
2answers
357 views

Performance effect of indexing foreign keys

My database is for an HR application with performance reviews and I am interested in whether I should index my foreign key. There are two tables involved. The first is a ratings table with 2 columns: ...
3
votes
2answers
701 views

Is there a standard for naming foreign keys when two columns reference the same table? [closed]

I've always used the name FK_CurrentTableName_ReferencedTableName. I just ran into a situation where I've got a table with CreatedById and ModifiedById both pointing to the same (users) table, so this ...
5
votes
1answer
10k views

How to get the foreign and primary key details for a table in SQL Server 2008

I would like to use 2 queries, one that lists all the foreign keys for a given table with the following information Schema name, foreign table name and the other that lists all the primary keys. Is ...
2
votes
1answer
6k views

Using a foreign key on multiple fields in one table

Simple question probably. For two tables. A one to many relation is created from A -> B, TeamID -> Fk_Team, however there are multiple fields that need to reference this one relationship how does ...
4
votes
2answers
25k views

How to Find the Foreign Key Associated with a Given Primary Key

All, I want a way to establish which columns in a given database are joined via PK/FK relationships. I can return the PK/FK information for a given table via SELECT * FROM ...
3
votes
1answer
31 views

Integrity Issues in this structure?

Imagine the situation. There are three tables, Student table[PK Student ID] Enrollment Table [PK EnrollID, FK Student ID] Fees Paid [PK Fee ID, FK EnrollID, FK StudentID] Edit: Fee_Paid Table ...
0
votes
2answers
64 views

What are some properties that a Foreign key must satisfy always?

I know about Primary Keys. PKs must satisfy: (1)Unique, (2) Not NULL, (3) Fully Functional Dependency, (4) Indexed.... these 04 properties. What are some properties that a Foreign key must always ...
0
votes
0answers
42 views

MySQL/MariaDB: Can I drop KEY declatations in sql dump for CREATE TABLE for foreign keys?

I prepare Liquibase schema creation changelog for legacy DB. I started with SQL dump and refined it by little sed processing so I have only CREATE TABLE statements. It looks like: CREATE TABLE ...
1
vote
1answer
76 views

Should child comment be treated as separate table?

I'm building a commenting system, currently my table indicates which comment is child with parent id in 1 table, I would like to know what is the best way of doing this? Current Table Scheme (1 ...
3
votes
2answers
36 views

Reasons to maintain FKs on an empty, deprecated table?

So I have a few dozen empty tables with foreign keys to other, populated tables. These tables are not being accessed by any CRUD operations, but have about 6-12 months before they can be unlinked from ...
4
votes
1answer
1k views

How to check foreign keys related to a table

How to see foreign keys related to a table in MySql? Background : I wanted to drop a table in MySql which has a foreign key constraint. When I do it I get this: Error Code: 1217. Cannot delete or ...
0
votes
0answers
40 views

SET FOREIGN_KEY_CHECKS=1; Commands out of sync; you can't run this command now

I am getting errors that I do not know how to solve using MySQL and php. The error is this... SET FOREIGN_KEY_CHECKS=1; Commands out of sync; you can't run this command now I am trying to run the ...
0
votes
1answer
46 views

is_not_trusted = 1 after Error-Free WITH CHECK CHECK CONSTRAINT

I'd like SQL Server 2005 SP4 to trust a certain foreign key constraint. Executing an ALTER TABLE statement that enables + checks the constraint returns Command(s) completed successfully yet ...
0
votes
1answer
30 views

Removing duplicate rows and changing related foreign keys in PostgreSQL

I have found all duplicate rows and now want to delete them after I update related foreign keys in other tables so they point to the correct row. How do I get a list of foreign keys related to my ...
0
votes
0answers
27 views

How to update a column with foreign key?

In two tables with a foreign key as CREATE TABLE table1 ( id int(11) NOT NULL AUTO_INCREMENT, PRIMARY KEY(id) ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE utf8_general_ci; CREATE TABLE table2 ( id2 ...
1
vote
1answer
67 views

“Merge” two rows in a Postgres table, with foreign keys

I am keeping a database of books I've read, using the following two tables in PostgreSQL: CREATE TABLE authors ( id SERIAL PRIMARY KEY, name text ); CREATE TABLE books ( id SERIAL ...
0
votes
1answer
23 views

Composite foreign key not verify all columns

Table1 (Num [PK NOT NULL], Dat [PK NOT NULL], ...) Table2 (ID [PK], Num, Dat, ...) I added this FK: ALTER TABLE [dbo].[Table2] WITH CHECK ADD FOREIGN KEY([Num], [Dat]) REFERENCES [dbo].[Table1] ...
1
vote
1answer
54 views

Discover missing foreign keys and/or indexes

We have a pretty big database (around 700GB of data), which has been inherited to us, and has had several DBAs. With time we've realized that there are several missing foreign keys and indexes. I'd ...
2
votes
0answers
41 views

Any drawbacks to referencing multiple tables from a single column?

I'm working on a system with the following entities: Projects Sections Activities There is one important constraint that needs to be enforced: Activities are always part of one project. ...