Top "Constraints" questions

A constraint is a condition that has to be fulfilled in a given context.

Two foreign keys reference one table - ON UPDATE SET NULL doesn't work

I've got two foreign keys in a table. Let's assume that table is called News and has foreign keys updatedById …

sql-server tsql foreign-keys constraints cascade
Error:"Key ... is not present in table"

I have a table with a character varying(12) field in it which is its PRIMARY KEY. I ran this query …

postgresql inheritance foreign-keys constraints search-path
Can I name my constraints with JPA?

When I use the maven-hibernate3-plugin (aka hbm2ddl) to generate my database schema, it creates many database constraints with …

database hibernate orm jpa constraints
'invalid for creating a default constraint' error when trying to add a constraint to an existing table

I want to add a default constraint using ALTER TABLE in SQL Server, but I received the below error message …

sql sql-server constraints alter-table
Safe area covered the view, can not remove

I don't know why the safe area covered my view on the iPhone X, simulator, but in xCode's view debug …

ios swift constraints iphone-x safearealayoutguide
Postgres constraint ensuring one column of many is present?

What are good ways to add a constraint to PostgreSQL to check that exactly one column (from a set of …

postgresql constraints
Width and Horizontal Position Are Ambiguous

it seems I have created a simple Image view with the following constraints: Align Center X to: Superview Align Center …

xcode swift constraints ambiguous
remove ON DELETE CASCADE

I have a child table. and foreign key there with ON DELETE CASCADE while creating the table. There are no …

sql constraints cascade alter
What's with Constraints in SwiftUI?

What is happening now with constraints in SwiftUI? Do View types adapt automatically for bigger devices etc. or what should …

ios swift constraints nslayoutconstraint swiftui
Techniques for Tracing Constraints

Here's the scenario: I've written some code with a type signature and GHC complains could not deduce x ~ y for …

haskell constraints ghc