Ruby on Rails: How do I add a not null constraint to an existing column using a migration?

Ruby on Rails: How do I add a not null constraint to an existing column using a migration?

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What is the purpose of constraint naming

sql database constraints naming

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Limit SQL Server column to a list of possible values

sql-server database constraints

database

How do I add a custom CHECK constraint on a MySQL table?

mysql sql database constraints check-constraints

database

Deferrable Constraints in SQL Server

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database

Can I name my constraints with JPA?

database hibernate orm jpa constraints

database

What is the difference between primary, unique and foreign key constraints, and indexes?

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database

Should I check for DB constraints in code or should I catch exceptions thrown by DB

database nhibernate exception-handling constraints unique

database

Fix ORA-02273: this unique/primary key is referenced by some foreign keys

sql database oracle constraints

database

Django: "Soft" ForeignField without database integrity checks

database django-models foreign-keys constraints

database

How to drop more than one constraint at once (Oracle, SQL)

sql database oracle constraints

database

postgres: constraint check and null values

database postgresql constraints

database

Unique constraint within a group of records where some value is the same

sql sql-server database sql-server-2005 constraints

database

Continuing a transaction after primary key violation error

sql database postgresql transactions constraints

database

Add constraint to make column unique per group of rows

database postgresql constraints unique-index partial-index

database