List:General Discussion« Previous MessageNext Message »
From:Paul DuBois Date:December 19 2002 6:40pm
Subject:RE: SELECT and UPDATE at the same time?
View as plain text  
At 13:23 -0500 12/19/02, <ir000387@stripped> wrote:
>Well, the only basis I have is personal experience from connecting to a local
>MySQL database. The components I use for connecting to MySQL with Delphi does
>cache the records as the server returns them. However, not all the records are
>returned at once.  As I said, it depends on how one connects to the server.

Okay.

If that's what you observe, I won't dispute it.  But then the behavior
is probably something specific to the Delphi interface.  The underlying
behavior of the client/server protocol is somewhat different than what
you observe, so people using other APIs will likely see something different
happening.

>
>If I'm wrong, then I apologize for any incorrect information that I may have
>given. Just trying to help.
>
>Dan Cumpian
>
>
>
>On Thu, 19 Dec 2002 00:18:48 -0600 Paul DuBois <paul@stripped> wrote:
>
>>  At 23:43 -0500 12/18/02, Dan Cumpian wrote:
>>  >Jeff,
>>  >
>>  >Not if your outer loop is in a separate query.
>>  In that case, your query
>>  >is essentially a cursor and is static once
>>  OPENed. As you move from
>>  >record to record, what you are seeing is the
>>  records at the time the
>>  >query was opened. Now, if you were to update
>>  records that you haven't
>>  >processed yet, then they may show up as
>>  modified in your outer query
>>
>>  Your basis for saying that?
>>
>>  >because (depending on how you are connecting
>>  to the database) the server
>>  >only returns several hundred rows at a time
>>  and caches them as you go
>>
>>  Your basis for saying that?
>>
>>  >through the record set. But that doesn't sound
>>  like it will impact you.
>>  >
>>  >HTH,
>>  >Dan Cumpian
>>  >
>>  >
>>  >-----Original Message-----
>>  >From: Jeff Snoxell
>>  [mailto:Jeff@stripped]
>>  >Sent: Wednesday, December 18, 2002 12:56 PM
>>  >To: mysql@stripped
>>  >Subject: SELECT and UPDATE at the same time?
>>  >
>>  >Hello again,
>>  >
>>  >I'm selecting a group of records from my
>>  database. I then loop through
>>  >the
>>  >selected records and do some work based on
>>  what I find. But what I also
>>  >want to do as I interrogate each record is
>>  update some of its fields
>>  >with
>>  >new values... but won't that screw up the
>>  outer loop? I mean if I try to
>>  >
>>  >execute a query whilst looping around the
>>  result set of a former query
>>  >will
>>  >I not screw up my result set that I'm looping
>>  through?
>>  >
>>  >Also, is it possible to update specific fields
>>  of certain records within
>>  >a
>>  >SELECT query? ie can I do something like this:
>>  >
>>  >SELECT * FROM my_table WHERE Age > 50 AND
>>  UPDATE Status = "OLD"
>>  >
>>  >Ta,
>>  >
>  > >Jeff

Thread
SELECT and UPDATE at the same time?Jeff Snoxell18 Dec
  • Re: SELECT and UPDATE at the same time?Paul DuBois18 Dec
    • Re: Re: SELECT and UPDATE at the same time?Jeff Snoxell18 Dec
      • RE: Re: SELECT and UPDATE at the same time?Mike Hillyer19 Dec
  • Re: SELECT and UPDATE at the same time?Gelu Gogancea18 Dec
    • Re: SELECT and UPDATE at the same time?Paul DuBois18 Dec
  • RE: SELECT and UPDATE at the same time?Dan Cumpian19 Dec
    • RE: SELECT and UPDATE at the same time?Paul DuBois19 Dec
RE: SELECT and UPDATE at the same time?ir00038719 Dec
RE: SELECT and UPDATE at the same time?Paul DuBois19 Dec
  • RE: SELECT and UPDATE at the same time?Dan Cumpian20 Dec