Perl脚本还是MySQL修复？

Question

I am a beginner in Perl and just got a tweak task with a perl scipt. The statement that I am focusing now is:

my $sth = $dbh->prepare('SELECT StringValue FROM CustomData WHERE (Record_ID = \'' . $ref->{'Record_ID'} . '\' && Field_ID = \'' . $metadata[11] . '\') LIMIT 1;');

The current statement will pull every record that matches the Record_ID value. However, it needs to be changed to only pull records where Record_ID begins with digit 1,2,9 .

I am thinking this is more like a regular expression issue, is that correct? If that is case, I should only be modifying the

 Record_ID = \'' . $ref->{'Record_ID'}

part. Is that correct? Or that should be something to be fixed in the prepare statement?

Answer 1

You should use placeholders instead of trying to interpolate your variables and try to do your own quoting. You might even consider using placeholders for the '1%' etc, unless you consider them static throughout all your queries.

my $sth = $dbh->prepare( q#
     SELECT StringValue FROM CustomData 
     WHERE (Record_ID = ? && Field_ID = ?) 
     AND (Record_ID LIKE '1%' OR Record_ID LIKE '2%' OR Record_ID LIKE '9%')
     LIMIT 1
#);

$sth->execute($ref->{'Record_ID'}, $metadata[11]);

Answer 2

Add an AND -part in your WHERE clause to filter the unwanted Record_IDs.

SELECT StringValue 
FROM CustomData \
WHERE (Record_ID = \'' . $ref->{'Record_ID'} . '\' && Field_ID = \'' . $metadata[11] . '\') 
AND (Record_ID  LIKE "1%" OR Record_ID  LIKE "2%" OR Record_ID  LIKE "9%")
LIMIT 1

Answer 3

To avoid masking the ' so many times you can use qq

my $sth = $dbh->prepare( qq§SELECT StringValue FROM CustomData 
                            WHERE (Record_ID = '$ref->{Record_ID}' AND 
                                   Field_ID = '$metadata[11]') LIMIT 1§
                       ) ;

Answer 4

You are right about changing the part Record_ID = \\'' . $ref->{'Record_ID'} . '\\' Record_ID = \\'' . $ref->{'Record_ID'} . '\\'

replace it with Record_ID LIKE \\'1%\\' || Record_ID LIKE \\'2%\\' || Record_ID LIKE \\'9%\\' Record_ID LIKE \\'1%\\' || Record_ID LIKE \\'2%\\' || Record_ID LIKE \\'9%\\'

Remove LIMIT 1 ,this only matches any one row,either of starting with 1,2 or 9

Here's how I think solution could go

my $sth = $dbh->prepare('
    SELECT StringValue 
    FROM CustomData 
    WHERE ( Record_ID LIKE \'1%\' || Record_ID LIKE \'2%\' || Record_ID LIKE \'9%\' 
    && Field_ID = \''. $metadata . '\');');

$sth->execute;

while (my @arr=$sth->fetchrow_array())
   {
   print @arr;
   }