How does a database handle multiple users at the same time?

How is a database structured so that multiple users can be accessing it, changing recrods, adding records, etc at the same time? How do database systems account for the possibilities that different changes are made to the same stuff?

4 Answers

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  • 1 decade ago
    Favorite Answer

    To control access to share data databases use the concept of "locks". If two people are working on the same data and the data is protected by a "write" lock, only one of the them can acquire the lock first and make changes. so the other guy has to wait till the first guy is through and releases the lock.

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    There are different "granularities" or types of lock. Till the time data is "dirty" (being updated by user A) the other users just get to see "stale" data. Once A is through everyone will see those changes.

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    google for transactions,concurrency control,isolation level etc.

  • 4 years ago

    A separate table for each consumer is a terrible concept, frankly...as long as userID is unique, there is not any clarification for it besides. only place your indexed columns right into a single table...then, in case you like the innovations for a given consumer or shoppers, do exactly the two pick despite FROM someTable the place userID = <single standards> pick despite FROM someTable the place userID IN <multiple standards>

  • Anonymous
    1 decade ago

    It's organized in the arrays of the data! Each data is stored under different arrays!

  • 1 decade ago

    Transaction Control.

    One of the first (and still used today) is CICS (Customer Information Control System). http://en.wikipedia.org/wiki/CICS

    For general information on transaction control see http://en.wikipedia.org/wiki/Database_transaction

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