Beefy Boxes and Bandwidth Generously Provided by pair Networks
Don't ask to ask, just ask
 
PerlMonks  

comment on

( [id://3333]=superdoc: print w/replies, xml ) Need Help??

Your code will remove all of the entries from the database (unless there is only one entry in @test), because for each element of @test it removes all the entries that are not equal to that element. You want to do the opposite: remove all the elements that are not represented in @test (i.e., not equal to _any_ of the entries in @test). So, you're looping over the wrong thing. Instead of looping over the list of things you don't want to delete, you want to loop over all the entries in the database and for each one you want to decide whether to delete it or not.

# This is untested. Test on sample data that # doesn't matter before using on live data. my %represented = map{$_=>1} @test; my $sth = $dbh->prepare("SELECT Name FROM tnt"); my $del=$dbh->prepare("DELETE FROM tnt WHERE Name=?"); $sth->execute(); while (my $line = $sth->fetchrow_hashref()) { if (not $represented{$$line{Name}}) { $del->execute($$line{Name}); } }

Update: minor optimization (prepare $del once outside the loop, instead of n times inside).


$;=sub{$/};@;=map{my($a,$b)=($_,$;);$;=sub{$a.$b->()}} split//,".rekcah lreP rehtona tsuJ";$\=$ ;->();print$/

In reply to Re: deleting from a mysql database by jonadab
in thread deleting from a mysql database by bory

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":



  • Are you posting in the right place? Check out Where do I post X? to know for sure.
  • Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
    <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
  • Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
  • Want more info? How to link or How to display code and escape characters are good places to start.
Log In?
Username:
Password:

What's my password?
Create A New User
Domain Nodelet?
Chatterbox?
and the web crawler heard nothing...

How do I use this?Last hourOther CB clients
Other Users?
Others admiring the Monastery: (5)
As of 2024-03-28 12:18 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    No recent polls found