SQL - referential integrity - Foreign key and Check constraint
Please let me know if below two declarations are same.create table R1( a INT PRIMARY KEY, b INT references K(w));Note: K is a table with single attribute w as primary keycreate table R1( a INT PRIMARY...
View ArticleForeign Key Settings
I will start by mentioning that I am very new to databases. I am working in MySQL.Can anyone give me a layman's view of when you would use which settings for the foreign key options so when you would...
View ArticleHow to store a (record which holds a) reference to any other column...
TL;DR: If the database schema should hold all the business logic, how is it be possible to specify that an attribute type is a reference to a specific attribute, instead of a specific record (as is the...
View ArticleLookup table for a one-to-many relationship
I have a tickets table with an id that I need to associate to a lookup table where the counterpart of that data is another id that is controlled from an outside source.tickets- id- sutfflookup-...
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Ensure data integrity in relational DB?
Let's imagine I want to store in a relational database the following :A list of quizzesA list of questions associated with quizzesA list of usersThe answers to questions made from users.I could have a...
View ArticleCreate foreign key constraint on indirect data
I am trying to enforce relational integrity across some database design containing sensor data. The relevant parts of the database:CREATE TABLE logger ( id INTEGER PRIMARY KEY);CREATE TABLE sensor (...
View ArticleDo any of the graph based/aware databases have good mechanisms for...
Do any of the graph-based/graph-aware databases (Neo4j, ArangoDB, OrientDB, or other) have mechanisms for maintaining referential integrity on a par with those offered by relational databases?I'm...
View ArticleLarge hexadecimal PRIMARY KEY - how to index substrings of the PK field?
I have a requirement for a very large (in terms of the number of rows, not data) database, and need to use a very long, unique, hexadecimal PRIMARY KEY instead of the usual AUTO_INCREMENT integer.As an...
View ArticleSQL Server - ensuring a complex relation on insert
I have some related tables:Application - stores a list of applicationsApplicationInstall - for each application, multiple installations are present (I have a foreign key...
View ArticleHow to delete foreign key with lots of references
Table B have several thousand records that references table A with a foreign key.The application sends a request to delete the row from table A. It's important that the synchronous operation would be...
View ArticleInconsistency in Relational Databases
I generally get confused when the term consistency is used. NoSQL tutorials always refer to the reads whereas Relational tutorials refer to a consistent state (ensuring referential integrity...
View ArticleWant to Set Relationship Between 3 Tables (1st Child Table column value...
I am using Visual Basic with a Microsoft SQL Server Database for my WinForms Application.I have 3 Tables - Purchases, Sales, Transactions (for payment/receipt)In the Transactions table, I am using...
View ArticleDesigning complex cross table data integrity checks
I am trying to start working on an application, and while I have some code the time has come to work on my database model as well. In the next sections I will describe what my application should be...
View ArticleConstraint - one boolean row is true, all other rows false
I have a column: standard BOOLEAN NOT NULLI would like to enforce one row True, and all others False. The are no FK's or anything else depending on this constraint. I know I can accomplish it with...
View ArticleNon-overlapping rectangles constrained to a boundary
I am trying to model placement of parts on a circuit board. Without anymeaningful constraints, my basic schema looks like this:create table part ( part_id bigserial primary key, name text not null,...
View ArticleConstraint to enforce "at least one" or "exactly one" in a database
Say we have users and each user can have multiple email addressesCREATE TABLE emails ( user_id integer, email_address text, is_active boolean)Some sample rowsuser_id | email_address | is_active1 |...
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How can I define circular referential integrity constraints?
I have two tables mutually referencing each other, and I get this error when trying to insert into one of them: "Foreign key constraint is incorrectly formed".I have been stuck for three weeks this...
View ArticleON DELETE CASCADE not working
Trying to implement a simple user follower system in MySQL, using a junction table:CREATE TABLE users ( id int NOT NULL AUTO_INCREMENT, email varchar(255) NOT NULL, username varchar(25) NOT NULL,...
View ArticleOracle parent child move failed
I have two tables, a parent and child table, which have referential integrity declared between two tables and try to move both the tables so I can delete rows.I start with the child table and the move...
View ArticleForeign key to multiple tables via forwarding table
Problem statementI have a table with a column whose values are foriegn keys, but thetarget table of the foreign key differs from row to row. The relevanttable can be determined from the key value...
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