updating a database

bory has asked for the wisdom of the Perl Monks concerning the following question:

Hello great perlmonks! I have a mysql database and i want to update some records from it, but instead of updating only those records it rewrites the whole database with the records updated and i lose the rest of the information. Here is my code:

my @name=("Anna","Maria","Carmen");
my @age=("25","27","29");
my @eyes=("brown","blue","pink");
#those arrays have always the same number of elements
for (my $i=0;$i<=$#name;$i++){    
                        
        my $sth=$dbh->prepare(qq{UPDATE tnt SET `Age`=\"$age[$i]\",`Ey
+es`=\"$eyes[$i]\" WHERE  `Name`=\"$name[$i]\"});
        $sth->execute();
        }
                $sth->finish;
[download]

If i have in the database the following entries:

Name     Age Eyes
Corina   13  red
Ada      17  blue
Anna     10  grey
Maria    2  white
Carmen   6
[download]

After updating in my way:

Anna 25 brown
Maria 27 blue
Carmen 29 pink
[download]

and i lose the other records. Thank you very much for your time

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Re: updating a database by Abigail-II (Bishop) on Feb 10, 2004 at 10:28 UTC
That sounds pretty hard to believe - and if it happens, it might as well be a MySQL error than a Perl issue. But my guess is that you either erase the other data somewhere else in your program, or that you start out with different data than you expect. I would also recommend you use placeholders. Not only will that make your code faster (you need just one prepare), you also have less problems with quoting. And what's the deal with backwacking the double quotes? And why put the column names in backticks? Why does the loop run till $i equals $#test, when the code doesn't show @test? Why don't you check the return values of the prepare and the execute? Abigail	[reply]
Re: updating a database by borisz (Canon) on Feb 10, 2004 at 09:44 UTC
I think the error is not in the update code. Boris	[reply]