Re: retrieve rows in a specified order

maikel7_at_poczta.onet.pl says...

> I'm new to the databases so I'm wondering why there is no concept of
> "row order" in many popular databases? There must be a reason for this.
> I thought I would find some simple commands in MySQL which would let me
> move rows up or down in a table, eg. "MOVE ROW...". Why don't they exist?

An RDBMS is *_not_* a spreadsheet. Tables in RDBMS's are not spreadsheets, even if there is a *_superficial_* resemblance.

One of the reasons the concept of row order doesn't exist is that RDBMS's have the idea of Transactions (even if MySQL doesn't!).

You say that you are new to databases, and that's fair enough. I suggest that you read about transactions, particularly in multi-user environments, and it should become clear to you why the concept of row order has no meaning.

A row order concept would work fine with one shop manager updating the table, but consider the issues in maintaining a row order if there were multiple updaters each committing and rolling back transactions many times a second.

At least that's my understanding of one of the reasons why the concept of row number is out for RDBMS's - anyone disagree?

Paul...  

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