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
237 views

Should I drop a foreign key if I use a soft delete?

"ON UPDATE" scenario never happens in my application. As soft delete is used, "ON DELETE" cascade and restrict scenario never happen as well now. Then, should I just drop foreign key because I have ...
2
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1answer
93 views

Conditionally join table

I'm new to database design and have designed a database that seems fine for the application but looks like it has a major red flag to me. I have a master table which is then joined to another table ...
2
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1answer
2k views

MySQL Foreign Key Prevents Deleting Table — But Table is Empty

Why would dropping an empty table produce a foreign key error? In MySQL, I have a table with the following definition CREATE TABLE `enterprise_rma` ( `entity_id` int(10) unsigned NOT NULL ...
2
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1answer
2k views

Is it possible to force drop of mysql tables with FK?

For dropping a table in which a Foreign Key is used in other tables, it is necessary to drop all other tables having FK connection with the corresponding table. Is there a short way to drop a table, ...
2
votes
1answer
113 views

How to enforce a nullable foreign key?

I have a relation between two tables. The foreign key table can have a row related in the primary table. There's a way to enforce the value of the FK column to be NULL or one of the values of the PK ...
2
votes
1answer
130 views

Unique foreign key constraint between three tables

I'd like to track appointment attendances. Visitors can have appointments, or they can just turn up. If they have an appointment, and miss it, in which case I'd like to record a reason for the missed ...
2
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1answer
1k views

foreign key constraints on same table

I have a table structure like this. tblquestion ( nQuestionId1 INT UNSIGNED PRIMARY KEY AUTO_INCREMENT NOT_NULL, nQuestionId2 INT UNSIGNED ALLOW NULL ); Here..nQuestionId2 has a foreign key ...
2
votes
1answer
131 views

Constructing Circularly Referenced Tables

I'm attempting to construct two tables in Oracle, A and B; each of these tables reference each other. In my script, I have the foreign key constraints 'in-line' of the create table statements. Of ...
2
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1answer
954 views

How can I check the integrity of disabled foreign key relationships for each individual table? (SQL Server 2008)

I'm porting a huge legacy database that many different legacy frontends depend on. When I'm finished, a new frontend will be running alongside all the old legacy frontends minus the frontend I ...
2
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1answer
118 views

Have foreign key constraint and index key for the same column(s)

I am creating a composite index key for 2 columns and then adding foreign keys to its appropriate table. Do I need to create a multiple index key reference and then create separate foreign keys? My ...
2
votes
2answers
121 views

Unique across tables

I have a table containing users. Each user has a primary email and a flag indicating if the user is deleted or not (we never hard-delete users). However, each user can also have additional emails. ...
2
votes
2answers
164 views

Foreign key set to cascading but fails to update - why?

As mentioned elsewhere, I am rather new to SQL and databases. Getting my hands dirty at the moment and trying all the different possibilities. I have a server running MySQL and set up the following ...
2
votes
1answer
3k views

Error Creating Foreign Key in Oracle

I have 2 tables: PRODUCTS PREFIX SUFFIX ATTR1 ATTR2 ----------------------------------------------------- 001 AAA 50 100 001 BBB 20 300 010 ...
2
votes
1answer
10k views

How to solve the error Msg 547, Level 16, State 0, Line 1 [closed]

Please suggest me how to solve the error How to solve the error Msg 547, Level 16, State 0, Line 1 The ALTER TABLE statement conflicted with the FOREIGN KEY constraint "MyForeignKeyName". The ...
2
votes
3answers
1k views

Altering table Foreign Keys produces an error (errno:150) (MySQL)

This is the first database I set up so I apologize if my problem is something obvious. I'm playing around with my table design and tried to create some link tables with FKs to avoid redundant data. ...
2
votes
1answer
568 views

MySQL Unique Index Keylength

I am hashing keys from one table that provides a 256 bit (64 char length) alphanumeric string that I intend to use in a second table as a foreign key. The engine of choice here is InnoDB. There are ...
2
votes
2answers
4k views

MySQL - automatically update all references to specific table to use on delete cascade?

I have a specific table for one of my software packages on a MySQL 5.1 box which I need to drop a few hundred entries. These are user names with names in uppercase, the application is case specific ...
2
votes
1answer
97 views

Linking identifiers across tables in MySQL (Foreign Keys)

Given a simplified example of two tables table Contact(ID int primary key, Name text not null) table ContactPhone(ContactID int not null, PhoneNumber text not null) Is there a way to tell MySQL ...
2
votes
1answer
681 views

Question on Design for User + User Groups + User Types + Subscriptions Model

I am redeveloping an existing web application with both weak source code and a weak underlying database design. I'm trying to develop things in a way that future expansion will be much easier, ...
2
votes
1answer
49 views

MySQL server won't start with foreign_key_checks=0

I'm running Ubuntu with MySQL version 5.5.44 mysqld Ver 5.5.44-0ubuntu0.14.10.1 for debian-linux-gnu on x86_64 ((Ubuntu)) I have a DB with foreign keys. I would like to have the foreign key ...
2
votes
2answers
210 views

Is it acceptable to have circular foreign key references\How to avoid them?

Is it acceptable to have a circular reference between two tables on the foreign key field? If not, how can these situations be avoided? If so, how can data be inserted? Below is an example of ...
2
votes
1answer
47 views

Is there any point in specifying the precision and scale of a number for a foreign key?

I am running Oracle 11gR2 11.2.0.3. I have two tables: table1 contains a column named SUBJECT_ID, whose datatype is NUMBER(7,0) (numbers range from 13 to 48480) table2 contains a a column named ...
2
votes
1answer
113 views

Is it possible to create a foreign key with a condition?

I have a table site that has a field categoryid_root and a table category which has the fields id and parentid I want to create a relationship between: site.categoryid_root and category.id but with ...
2
votes
1answer
6k views

Column name or number of supplied values does not match table definition error

I have a table, with two foreign keys defined on two columns of that table. The problem is that, when I insert the values from SQL Server, I get an error: Column name or number of supplied values ...
2
votes
1answer
137 views

Foreign Keys to tables where primary key is not clustered index

I'm focusing on SQL Server here, but I think this is a database agnostic question, really. I have a table whereby a Guid is logically the primary key. However, uniqueidentifiers apparently make ...
2
votes
1answer
4k views

Composite primary key from multiple tables / multiple foreign keys

I want to build a composite primary key made up of foreign keys from two different tables. I'm still pretty green to this... A great answer was given to building a composite key from multiple foreign ...
2
votes
1answer
281 views

Do you need to include all foreing keys of a parent table in the child table?

Suppose you have a table my_table ----------- id name foreign_id And you are creating another table that will reference my_table. I think that this would be enough: other_table ----------- id name ...
2
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1answer
268 views

InnoDB Foreign key updating vs. manual in-application updating

I've been working on a "legacy" schema in MySQL Workbench that uses a lot of relations. All of the tables are MyISAM, however, and there are no foreign keys. However, I'm working on a new area of the ...
2
votes
1answer
32 views

Should I create many ID for a same Person/entity in my DB?

In my model, I must store the name of the teacher of some kids and the classroom in which the teachers work, let’s say. All of the hundreds of teachers in the schools have 1 and only 1 classroom, ...
2
votes
1answer
79 views

Efficient manual cleanup of foreign keys in MySQL [closed]

I have an all-InnoDB database in MySQL (Percona) 5.6 that was previously using FK constraints. I had to give up on them as I kept running into locking issues, so I removed the constraints and added ...
2
votes
1answer
101 views

Foreign key, key split in two tables

I have to record a list of events made of action, reason (optional, may be multiple), user. I have a master table with all the valid action, and another with all the valid action-reason combination. ...
2
votes
1answer
111 views

Can triggers be used to implement automated polymorphic association?

(Apologies for any bad formatting or ignorance of common practices within this community; this is my first question here.) I'm attempting to (re)design a MySQL database for a personal social ...
2
votes
1answer
99 views

Relational modeled design to store versioned files

The scenario I have images in a database table and some of these need to be altered then re-saved(not overwriting the original) whilst providing a reference back to the original. I also save the ...
2
votes
2answers
334 views

How to establish a Two-to-One table relationship (PK-FK-CK)?

My question is about DB design and its principles. I am working on a Python application where objects are mapped to database tables. I have Projects and People objects, mapped to their respective ...
2
votes
3answers
492 views

Many to many link tables with history? [closed]

While creating a PostgreSQL database of customer subscribed services with DNS domains, I want to: enable customers to subscribe to multiple services each service can have multiple domain names per ...
2
votes
2answers
1k views

Two primary keys to one foreign key

racing_couple ID (PRIMARY) breeding_couple ID (PRIMARY) egg IDpar(FOREIGN KEY) I have 2 IDs from 2 different tables (racing_couple and breeding_couple) and they are primary keys. In 3. table (egg) ...
2
votes
1answer
2k views

prevent MySQL Workbench to add index for foreignkey constraint when it is first part of primary

I know for each foreign key we should make an index on its column, But it is not necessary when that column in first part of PRIMARY index. MySQL accepts this query: CREATE TABLE IF NOT EXISTS ...
2
votes
1answer
933 views

Foreign key with multiple table options

I'm not sure if the title is very good, feel free to suggest a better one. People can "comment" on different objects of my site,similarly to StackExchange (for example they can comment on a Question, ...
2
votes
1answer
717 views

Will a row update check all child tables which have foreign key relationships in InnoDB?

I have a master table and around 60 to 70 child tables, all are InnoDB tables and have foreign key relationships with the master table. Foreign key relations are On-Delete Cascade and On-Update ...
2
votes
1answer
141 views

InnoDB foreign key and index duplication?

I'm have a part table like this: part_id INT manufacturer_id INT supplier_id INT part_number VARCHAR(50) part_description VARCHAR(120) with foreign ...
2
votes
1answer
60 views

Can Indexes mitigate untrusted Constraint

I using sp_blitz and found two tables that have foreign keys that is untrusted. tried to enable the trust with: ALTER TABLE MyTableName WITH CHECK CHECK CONSTRAINT MyConstraintName; GO But got this ...
2
votes
0answers
17 views

SQLITE Foreign key has to be re-added? [closed]

Currently I have a mysql database on my computer which I convert to sqlite database. On the sqlite database, I have transaction_detail table with a foreign key to transaction_master table. The ...
2
votes
1answer
70 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 ...
2
votes
0answers
81 views

Storing URLs in a database

I am thinking about storing URL's in my database, but I am not sure whether the way I use is an efficient way to do things or not. Table name : url url_id (Primary Key & Auto Increment) url_value ...
2
votes
0answers
345 views

AFTER DELETE trigger will not fire during a cascade delete

I've got two tables, corresponding to Nodes in a graph and Aisles to which they may belong. In addition, each Aisle has a Node at which it starts and ends. Aisle Table: Aisle char(4) Start_Node ...
2
votes
0answers
35 views

See indices implicitly created for foreign key constaints in MySQL

When I add a foreign key constraint to my table, SHOW INDEX doesn't show any new indices, but the overall space used by the indices in that table increases. Apparently, the index for the field I put a ...
2
votes
0answers
148 views

Is it recommended to have redundant foreign key columns?

Imagine I have the models A, B, C e D, where A have many Bs, B have many Cs and C have manyDs: Without redundance A | id | ... | ------------ | ... | ... | B | id | a_id | ... | ...
2
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1answer
129 views

Deferrable Foreign Key Constraints

What are the consequences of making a foreign key constraint DEFERRABLE INITIALLY IMMEDIATE instead of NONDEFERRABLE? This answer on StackOverflow mentions the performance impact that comes with no ...
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vote
3answers
94 views

Need suggestion for placing foreign keys in the databases

I have the database for customers. The customers table is something like this +------------------+ | Customers | +------------------+ | id (PK) | | business_email | | business_name ...
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vote
3answers
8k views

Difference between On Delete Cascade & On Update Cascade in mysql

I have two tables in MySQL database- parent, child. I'm trying to add foreign key references to my child table based on the parent table. Is there any significant difference between ON UPDATE CASCADE ...