checking mysql rows continuously

[bigup401]

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[LanX]

these are mostly SQL questions, not Perl.

Well ... to get you started with DBI

> then how can i run the query continuously

->fetchrow ° will give you row after row if you don't LIMIT you can run it in a loop

> skip to next row if the previous one status eq to no

• either you select status too and decide in Perl to go to the next loop iteration
• or if no action is needed you insert a where clause WHERE status == "yes"

I recommend you use DBI#fetchrow_hashref

Fetches the next row of data and returns it as a reference to a hash containing field name and field value pairs. ...

If there are no more rows or if an error occurs, then fetchrow_hashref returns an undef

something like

my $query = $dbh->prepare("SELECT * FROM items ORDER BY created ASC");
+   

$query->execute();

while ( my $h_fields = $query->fetchrow_hashref() ) {
    next if $h_fields->{status} eq 'no';                # not needed w
+ith WHERE clause
    ...
}

(untested)

Please see SQL tutorials

UPDATE

°) uhm ... DBI has no fetchrow! But ...

$ary_ref = $sth->fetchrow_arrayref;
$ary_ref = $sth->fetch;    # alias

down-voted for showing wrong code. (Again)

[bigup401]

thanks for your response, am going to try it now

[Anonymous Monk]

How about something vaguely like this ... an inner-join of a table to itself:

select A.id from table1 A inner join table1 B on (B.id = A.id - 1) where B.status = 'no' and A.status = 'yes'

I think that would give you the id's rows where a "yes" answer immediately follows a "no" answer. (It will not give you initial "yes" answers that are not followed by "no," so manually add "id#1" to your list.) Armed with this answer, select the rows with greater-or-equal IDs and walk them until you encounter a "no."

Although I think that this query will still require "a full table scan," at least it will be the database engine that's doing the heavy lifting.