Mysql automatically updating foreign keys katt williams internet dating rating

Posted by / 11-Jun-2016 07:59

Mysql automatically updating foreign keys

Without foreign keys, you are responsible for keeping track of inter-table dependencies and maintaining their consistency from within your applications.In some cases, doing this might not be much more work than issuing a few extra extra work, and if the database engine will perform consistency checks for you, why not let it?Automatic checking capability becomes especially useful if your tables have particularly complex relationships.You likely will not want to be responsible for implementing these dependencies in your applications.This is called "cascaded delete," because the effect of the delete cascades from one table to another. For example, with cascaded update, changing a student's table records.Foreign keys help maintain the consistency of your data, and they provide a certain measure of convenience.

i tried this: UPDATE person,member SET email = 'email X' WHERE email = 'email1'; If you have a primary key that you are going to want to update, then you have chosen a poor primary key.

It also allows you to place constraints on what may be done to the tables in the relationship.

The database enforces the rules of this relationship to maintain referential integrity. In other words, the foreign key prevents entry of scores for non-existent students.

Email address is definitely a poor choice for a PK, as people often change their email address.

What you might hope for is an "ON UPDATE CASCADE" option, but there isn't one.

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Foreign keys are not useful just for record entry, but for deletes and updates as well.

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