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If I understand what you are asking for: A given person can have multiple roles in a team but can only be on one team I would do it like this: By putting the TeamId in the People table you enforce the fact that a Person can only be on one team. You then have a many:many relationship using a cross join table between People and Roles. This allows a person ...


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This can be done with DDL alone but it's not at all trivial. The following will ensure that any test will either have 0 or 5 test cases: create table test ( test_id integer not null, constraint pk_test primary key (test_id) ) ; create table test_case ( test_id integer not null, case_no smallint not null, ...


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What you are doing is impossible because the INFORMATION_SCHEMA database is a database made up of in-memory read-only temporary tables (See my post How is INFORMATION_SCHEMA implemented in MySQL?) You are going to have to drop the triggers and recreate them I wrote a post on that before (Oct 02, 2011 : Can mysqldump dump triggers and procedures?) Here is ...


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Your comment about intensive dropping and creating and the notice you received regarding increasing max_locks_per_transaction hint that you're dropping and creating many objects in the same transaction. Each of those results in a lock, which each requires a small amount of shared memory. Because of this, max_locks_per_transaction limits the number of locks ...


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What I would suggest to you before putting a lot of work into designing a system, is to take a leaf from the book of the great Issac Newton - "If I have seen further it is by standing on the shoulders of giants". By this I mean take a long hard look at what's been done already - there are systems that could be of interest to you in this domain - take a ...


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Neo4j is a schema-optional graph database. You could choose to enforce a full schema and reap the benefits.


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Check this out, and links within (1, 2). InnoDB has a limit of 4 billion tables. There is no compelling reason to use the file system to store data that is better stored in a database. Take a look here to see that virtually every form of social networking software uses an underlying database - normally MySQL or PostgreSQL (which I would recommend). 2 ...



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