HOW IS TRANSACTION ISOLATION LEVEL SET VS SESSION.tx_isolation?

This is a basic question or so I believe!

Where and how do you set a current transaction isolation setting
I checked @@session.tx_isoation an @@tx_isolation are the same

so what variable or sql command sequence  sets things such that it is either transaction specific to a specific transaction or the default for just begin end transactions???

there is supposed to be three different setting but I found only 2 so far: session and global
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Robert SilverSr. Software EngineerAsked:
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Steve WalesSenior Database AdministratorCommented:
(oops, ignore me, I gave you MSSQL advice, removing my comment, sorry about that)

However, in case you hadn't found it, since I've got a comment stuck here anyway, here's the link to the docs on isolation level for MySQL.

http://dev.mysql.com/doc/refman/5.0/en/set-transaction.html
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Robert SilverSr. Software EngineerAuthor Commented:
I know not much help I need specifics not given at your link
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Steve WalesSenior Database AdministratorCommented:
Sorry can't help you ... I don't know much about MySQL, mis-read it as MSSQL and replied based on that :-/
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Robert SilverSr. Software EngineerAuthor Commented:
This question may not have an easy answer or even be so relevant.
I had heard  of this setting and wish to know how it is set that is all
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Robert SilverSr. Software EngineerAuthor Commented:
Perhaps the real answer here is the session becomes specific to a given Transaction given
it is within the same session but then why make the distinction?
Was that just a mistake that was made and there is no such setting at all?
That would be my current  thoughts on this?
With Multi-threading it just occurred to me that maybe I could set off one transaction or multiple transactions within the same session but I guess that is not possible given the response here

Anyone like to comment on that?
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Mark WillsTopic AdvisorCommented:
If I understand your question properly... You are correct, there are three.

The basic syntax is :
mysql> SET <extent> TRANSACTION ISOLATION LEVEL <level>;

You must specify the extent as being GLOBAL or SESSION and if neither keyword is mentioned, then it is for the next (unstarted) transaction only.

There are 4 levels (in sequence of increasing guaranteed integrity) :
READ UNCOMMITTED
READ COMMITTED
REPEATABLE READ
SERIALIZABLE

The  REPEATABLE READ level is the default...
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Mark WillsTopic AdvisorCommented:
Found an example for you at the transaction level and the results / outcomes between two sessions...

http://dba.fyicenter.com/faq/mysql/Change-Transaction-Isolation-Level.html
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Robert SilverSr. Software EngineerAuthor Commented:
I've requested that this question be deleted for the following reason:

No interest
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Mark WillsTopic AdvisorCommented:
Interesting to say "no interest"

There was an example given of how to set and test for current transaction, and previously, the three different methods used to set the isolation level... being Global or Session and if neither of those two keywords are mentioned, then it is Transaction.
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Robert SilverSr. Software EngineerAuthor Commented:
I've requested that this question be deleted for the following reason:

No decent answer or interest
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MySQL Server

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