InnoDB Database

[Anon]

hi,

i have a question concerning innodb.
i'm running a innodb because of the
transactions but i have one "problem".

if i want to display a value (e.g.
in an admin) and want to change it
safely how can i do it ?

i can't left the row locked because
php closes connection ?

is the only possibility to check
the value before update it and so
to be sure that it hasn't changed ?

overview:
1-table t1's tableformat is innodb.
2-a row from t1 is read
3-output to browser (of client)
4-user edtis
5-update to t1

db:
2-select * ... (for update is useless here)
5:
begin;
select value from id for update;
<<check if value is identical to 2>>
update value ....
commit;

is there another way to do it ?

how can i guarantee that the value
that is overwritten in 5 is identical
to 2 ?

[[deleted]]

"how can i guarantee that the value
that is overwritten in 5 is identical
to 2 ?"

You can't with just SQL, you'll have to use a manual locking method.

Add a column to the table, and call that something like 'lockdate'.

When you select records to display them to in the browser, you make sure that you only select records that have no 'lockdate' value. When you have records selected and you want to display them on a browser, you update the 'lockdate' column for those records, and you enter the current date and time.

When you process the submitted values from the form, you can safely update the rows with the new values, and reset the lockdate value to NULL.

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[Anon]

okay thanks for the suggest 🙂.