Training, Open Source computer languages
PerlPHPPythonMySQLApache / TomcatTclRubyJavaC and C++LinuxCSS 
Search for:
Home Accessibility Courses Diary The Mouth Forum Resources Site Map About Us Contact
 
For 2023 (and 2024 ...) - we are now fully retired from IT training.
We have made many, many friends over 25 years of teaching about Python, Tcl, Perl, PHP, Lua, Java, C and C++ - and MySQL, Linux and Solaris/SunOS too. Our training notes are now very much out of date, but due to upward compatability most of our examples remain operational and even relevant ad you are welcome to make us if them "as seen" and at your own risk.

Lisa and I (Graham) now live in what was our training centre in Melksham - happy to meet with former delegates here - but do check ahead before coming round. We are far from inactive - rather, enjoying the times that we are retired but still healthy enough in mind and body to be active!

I am also active in many other area and still look after a lot of web sites - you can find an index ((here))
Mysql in Perl

Posted by revtopo (revtopo), 2 October 2007
hi there,

I have got to execute two sql queries in a program. In this the result from the first should be used in the second query as a condition.

say $sequence is the result from the first query which has to be used in the second query as a condition. there are about 10 $sequence.

my second sql query is similar to this.

select rna_sequence, hit_string, hit_target, sequence_db from Hsp where rna_sequence  = '$sequence' and sequence_db = '1069'

so, my questions is,  is that correct to use $sequence directly in the place that i have used if notcould you suggest any other method to do.

thanks

Posted by admin (Graham Ellis), 2 October 2007
You're correct in principle, I think ... but as you don't give a code example I can't say whether of not you've correctly assigned the data from the first query into that $sequence variable.

Posted by revtopo (revtopo), 2 October 2007
my $sequence;
my $dsn = qq(DBI:mysql:database=$database; host=$host);
$connect = DBI-> connect($dsn, $user, $pass,{printError =>1}) or die $DBI::errstr;
my $query = $connect->prepare(qq(select rna_sequence_sequence, count(rna_sequence_sequence) as count, miRNA  from Cloned_rna where length(Rna_sequence_sequence) = 21 and miRNA is null group by Rna_sequence_sequence order by count desc limit 10  ));
$query->execute;
while (my( $sequence, $count, $miRNA) = $query->fetchrow_array()){
$miRNA='N' unless defined $miRNA; # gives the undefined mirna a value since they are null
$sequences{$sequence}= $count;
}
foreach my $sequence (sort keys %sequences) {
print "$sequence\t$sequences{$sequence}\n";
}

my $query1 = $connect->prepare(qq(select accession, hit_start, hit_end, Rna_sequence_sequence, hit_string, sequence_idsequence_db from Hsp where rna_sequence_sequence = '$sequence' and Sequence_db_idSequence_db ='1069' limit 10));
$query1->execute;
while (my ($accession, $hit_start, $hit_end, $Rna_sequence_sequence, $hit_string, $sequence_idsequence_db) = $query1->fetchrow_array()){
print "$accession, $hit_start, $hit_end, $Rna_sequence_sequence, $hit_string, $sequence_idsequence_db\n";
}

please note that ma using strict in my program

Posted by admin (Graham Ellis), 2 October 2007
You are getting 10 results back and just using the last of the 10 values of $sequence in your second query.  That's fine if it's what you want to do, but I suspect you really wanted to a do a loop there ...

.... which ....

.... deep breath ....

points me to wards suggesting you do the whole thing using a Join in MySQL.



This page is a thread posted to the opentalk forum at www.opentalk.org.uk and archived here for reference. To jump to the archive index please follow this link.

You can Add a comment or ranking to this page

© WELL HOUSE CONSULTANTS LTD., 2024: Well House Manor • 48 Spa Road • Melksham, Wiltshire • United Kingdom • SN12 7NY
PH: 01144 1225 708225 • FAX: 01144 1225 793803 • EMAIL: info@wellho.net • WEB: http://www.wellho.net • SKYPE: wellho