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This is just another way SQL databases are quite different from flat file databases. SQL databases aren't just data repositories, they're also tools for managing data. Typically, any program that accesses a SQL database has to connect as a specific user, and you can decide what sorts of data operations that user can perform.
Creating a user
I'm still struggling a little bit with the Control Center, probably because it has different modes of use rather than what I would call a unified interface.
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There's a brief mention in the tutorial of the need to modify the installation process to include steps needed to set up client/server access.
The query editor
Page 296 of the tutorial goes into some detail on queries, which were touched on earlier in the tutorial.
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