There are a couple of exceptions though: While not really the subject of this post, My SQL Workbench is a great tool for database developers and one of the features is the creation, modification and reverse engineering of schemas.
My SQL is by far the most popular database management system for small- to medium-sized web projects.
My SQL CONSTRAINT is used to define rules to allow or restrict what values can be stored in columns.
The purpose of inducing constraints is to enforce the integrity of a database.
The UNIQUE constraint maintains the uniqueness of a column in a table.
Foreign Keys is a feature requested by many, many people and has often been cited as the reason for not being able to replace Inno DB with My SQL Cluster when they needed the extra availability or scalability.
Note that this post is an up-version of the original – and was first published with the 7.3 labs release in June 2012.
Partitioned tables cannot contain foreign keys, and cannot be referenced by a foreign key.
Note: Maria DB accepts the REFERENCES clause in ALTER TABLE and CREATE TABLE statements, but that syntax does nothing.