I have currently working on perl script.
Select Column1,Column2,Column3.. from table.
This query contain some part in $cmd="Select Column1 ";
and other $cmd1=",Column2,Column3 from table"; // This is dynamic part, so split query in two different variable.
After this execute whole query.
How to do this query splitting part.?
use DBI;
use strict;
use warnings;
# Your input !
my $cmd = "Select Column1 ";
my $cmd1 = ",Column2,Column3 from table";
# I am wondering why you have your query like this ...
# but anyway, lets assume there's a reason behind this!
my $dbh =
DBI->connect(
'DBI:mysql:databasename;host=db.example.com', # TODO Change this
'username', # TODO change this
'password', # TODO change this
{ RaiseError => 1 }
) or die "Could not connect to database: $DBI::errstr";
my $sth = $dbh->prepare( $cmd . $cmd1 );
$sth->execute();
my #row;
while ( #row = $sth->fetchrow_array ) {
print "#row\n";
}
I can't seem to figure out the issue with my .pm file and script. I am fairly new to Perl.
I have a database with name "project" and there is table with name "mailing".
mailing table has 7 entries, which I want to display using module.
So, I have this custom module to log in to database and do a query. This module is names as DB.pm
DB.pm is stored on my FEDORA 20 at /root/mysql/GUI/DB.pm.
DB.pm is defined as follows:
package GUI::DB;
use strict;
use DBI;
use vars qw(#ISA #EXPORT);
use Exporter;
#ISA = qw(Exporter);
#EXPORT = qw(dbConnect query);
#
# dbConnect - connect to the database, get the database handle
#
sub dbConnect {
# Read database settings from config file:
print "Works";
my $dsn = "DBI:mysql:project";
my $dbh = DBI->connect( $dsn,
'root',
'mydatabasepassword',
{ RaiseError => 1 }
);
return $dbh;
}
#
# query - execute a query with parameters
# query($dbh, $sql, #bindValues)
#
sub query {
my $dbh = shift;
my $sql ="SELECT * FROM mailing";
my #bindValues = #_; # 0 or serveral parameters
my #returnData = ();
# issue query
my $sth = $dbh->prepare($sql); //**line number 39 that is giving** error
if ( #bindValues ) {
$sth->execute(#bindValues);
} else {
$sth->execute();
}
if ( $sql =~ m/^select/i ) {
while ( my $row = $sth->fetchrow_hashref ) {
push #returnData, $row;
}
}
# finish the sql statement
$sth->finish();
return #returnData;
}
1;
Now I want to use this module inside my per script. This is what I tried:
#!/usr/bin/perl
use warnings;
use strict;
use lib '/root/mysql/';
use GUI::DB qw(dbConnect query);
dbConnect();
query();
This is the error I'm getting -->
Can't call method "prepare" on an undefined value at /root/mysql/GUI/DB.pm line 39.
Please help me with this. I am not sure how to proceed. I am guessing it has something to do with argument passing. Nothing is wrong with database. It works fine from CLI.
Thanks :)
_x_X_X_X_X_X_X_X_X_X_X_X_X_X_X_X__X_X_X_X_X__X
TILL HERE IT IS RESOLVED
_X_X_X_X_X_X_X_X_X_X_X_X_X_X_X_X_X__X_X_X
FURTHER ISSUE is SQL command is not working.
In the mailing table of my database I have email id with different domains.
For example, some id's are xyz#gmail.com, 12343#gmail.com , bae#yahoo.com as so on and I am assuming new email ids will be added to mailing tables every day with different domains.
I am trying to write a scripts that updates another table which holds a daily count of email addresses by their domain name. This is what I tried:
#!/usr/bin/perl
use warnings;
use strict;
use lib '/root/mysql/';
use 5.016;
use Data::Dumper;
use GUI::DB qw(dbConnect query);
my $data = dbConnect();
my #domain = query($data, "SELECT substr(addr,locate('\#',addr)+1) as maildomain, count (*) as mailcount FROM mailing GROUP BY maildomain ORDER BY mailcount DESC");
for my $key (#domain){
say Dumper ($key);
}
But I am getting an error,
You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near '*) as mailcount FROM mailing GROUP BY maildomain ORDER BY mailcount DESC' at line 1 at /root/mysql/GUI/DB.pm line 44.
Same SQL statement works from CLI with no issues.
Any help would be appreciated. :)
1) Your error is saying that $dbh is undefined here:
sub query {
my $dbh = shift;
...
# issue query
my $sth = $dbh->prepare($sql); #<***LOOK HERE***
...which means $dbh must be undefined here:
sub query {
my $dbh = shift; #<***LOOK HERE***
...
# issue query
my $sth = $dbh->prepare($sql);
2) Let's see why. Your dbConnect() method returns $dbh:
sub dbConnect {
# Read database settings from config file:
print "Works";
my $dsn = "DBI:mysql:project";
my $dbh = DBI->connect(
$dsn,
'root',
'mydatabasepassword',
{ RaiseError => 1 }
);
return $dbh; #<***LOOK HERE*****
}
3) But, you call dbConnect() like this:
dbConnect();
Because you never save the return value anywhere, $dbh is discarded.
4) Furthermore, you call query() like this:
query();
Yet, you defined query() like this:
sub query {
my $dbh = shift;
The query() sub believes that the first argument will be the database handle--but you didn't call query() with any arguments.
You need to do this:
my $data_base_handle = dbConnect();
my #results = query($data_base_handle);
#do something with #results
Response to comment:
I printed #results, this is what I see HASH(0x1d05be8)
HASH(0x1d05ba0) HASH(0x1d05b58) HASH(0x1d05b10) HASH(0x1d05ac8)
HASH(0x1d05a80) HASH(0x1d05a38)
You wrote:
my $row = $sth->fetchrow_hashref;
...which asks DBI to return each row as a reference to a hash. Then you wrote:
push #returnData, $row;
...which pushed each hash reference into an array. So query() returns an array of hash references. The notation HASH(0x1d05be8) is what perl outputs when you print a hash reference.
If you want to see what's in those hashes, then do this:
use 5.016; #enable say()
use Data::Dumper;
...
...
for my $href (#results) {
say Dumper($href);
}
To access the data in a hash reference, you can do this:
use strict;
use warnings;
use 5.016;
use Data::Dumper;
my $href = {
c => 3,
a => 1,
b => 2,
};
my %hash = %{$href}; #dereference, {}, the reference into a hash, %
for my $key ( keys %hash ) {
say "$key $hash{$key}";
}
--output:--
c 3
a 1
b 2
Response to next comment:
(Answer posted in comments under op.)
By the way, perl is pretty good at text processing, so if you couldn't figure out the problem with your query, you could process the email addresses with perl:
use strict;
use warnings;
use 5.012;
use Data::Dumper;
use DBI;
use DBD::mysql;
# CONFIG VARIABLES
my $db_type = "mysql";
my $database = "my_db";
my $host = "localhost";
my $port = "3306";
my $user = "root";
my $pword = "";
# DATA SOURCE NAME
my $dsn = "dbi:$db_type:$database:$host:$port";
# PERL DBI CONNECT
my $dbh = DBI->connect($dsn, $user, $pword);
# PREPARE THE QUERY
my $tablename = "mailing";
my $select =<<"END_OF_SELECT";
select addr from $tablename
END_OF_SELECT
my $addr_aref = $dbh->selectcol_arrayref($select); #Returns a reference to a flat array containing all the email addresses
$dbh->disconnect;
my %count_for;
for my $addr (#{$addr_aref}) {
$addr =~ s/.*#//;
$count_for{$addr}++;
}
say Dumper(\%count_for);
--output:--
$VAR1 = {
'google.com' => 2,
'gorilla.com' => 1,
'yahoo.com' => 3
};
I've researched a bit and found that using mysql_use_result=1 is supposed to alleviate the memory issue. However, since I am new to this DBI module I don't understand what is happening here:
#!/usr/bin/perl -w
use strict;
use DBI;
my $dbh = DBI>connect('DBI:mysql:blah;host=blah.blah.blah.blah;mysql_use_result=1','blah','blah',{RaiseError => 1});
my $sth = $dbh->prepare('select * from TaqMinute where tradeDate<=\'2014-04-22\' and symbol<=\'AAPL\' ;') ;
if (defined($sth)) {
$sth->execute();
my #row;
while (#row = $sth-> fetchrow_array()) {
print "#row\n" ;
}
}
$sth->finish();
$dbh->disconnect
Before I added mysql_use_result=1, the script would fail after about 1.5 minutes complaining that it ran out of memory. After adding this my query arguments are ignored and I simply get all the data in the database.
Any ideas how to help me or how to use this switch properly? Btw, the database that I am querying is very large.
Thanks in advance!
Craig
Try to use parametized queries, maybe something wrong with your qoutes.
my $dbh = DBI>connect('DBI:mysql:blah;host=blah.blah.blah.blah','blah','blah',{RaiseError => 1});
my $sth = $dbh->prepare_cached('select * from TaqMinute where tradeDate<=? and symbol<=?') ;
die "sth undef!" if ! defined $sth;
$sth->execute('2014-04-22','AAPL');
while (my $rowref = $sth->fetchrow_arrayref()) {
print Dumper($rowref) ;
}
$sth->finish;
I am trying to insert a record into a MySQL database using Perl DBI. I am not getting any errors but the insert is not working. However, I am able to successfully fetch records from the database using DBI.
Here is the code that does the insert:
#!"C:\xampp\perl\bin\perl.exe"
use diagnostics;
use DBI;
use strict;
use warnings;
my $driver = "mysql";
my $database = "mysql";
my $dsn = "DBI:$driver:database=$database";
my $userid = "root";
my $password = "password";
my $buffer;
my #pairs;
my $pair;
my $name;
my $value;
my %FORM;
# Read in text
my $ENV;
$ENV{'REQUEST_METHOD'} =~ tr/a-z/A-Z/;
if ($ENV{'REQUEST_METHOD'} eq "GET")
{
$buffer = $ENV{'QUERY_STRING'};
}
# Split information into name/value pairs
#pairs = split(/&/, $buffer);
foreach $pair (#pairs)
{
($name, $value) = split(/=/, $pair);
$value =~ tr/+/ /;
$value =~ s/%(..)/pack("C", hex($1))/eg;
$FORM{$name} = $value;
}
my $first_name= $FORM{name};
my $address = $FORM{address};
my $city = $FORM{city};
my $occupation = $FORM{occupation};
my $age = $FORM{age};
my $dbh = DBI->connect("dbi:mysql:dbname=mysql", "root", "password",{ AutoCommit => 0,RaiseError => 1}, ) or die ("Couldn't connect to database: ") , $DBI::errstr;
# my $sth = $dbh->prepare("INSERT INTO persons
# (FirstName, LastName,Address,City)
# values
# ($first_name, $last_name,$address,$city)");
my $query = "insert into userrecords(Address,Age,City,Name,Occupation)
values (?, ?, ?, ?, ?) ";
my $statement = $dbh->prepare($query) or die ("Couldn't connect to database: "), $DBI::errstr;
$statement->execute($address,$age,$city,$name,$occupation) or die ("Couldn't connect to database: "), $DBI::errstr;
$dbh->disconnect();
my $URL = "http://.....:81/cgi-bin/showdata.cgi";
print "Location: $URL\n\n";
exit(0);
When I run my code in the Padre IDE, I get the following errors:
****Error*********
Useless use of a variable in void context at InsertRecord.cgi line 50 (#1)
(W void) You did something without a side effect in a context that does
nothing with the return value, such as a statement that doesn't return a
value from a block, or the left side of a scalar comma operator. Very
often this points not to stupidity on your part, but a failure of Perl
to parse your program the way you thought it would. For example, you'd
get this if you mixed up your C precedence with Python precedence and
said
$one, $two = 1, 2;
when you meant to say
($one, $two) = (1, 2);
Another common error is to use ordinary parentheses to construct a list
reference when you should be using square or curly brackets, for
example, if you say
$array = (1,2);
when you should have said
$array = [1,2];
The square brackets explicitly turn a list value into a scalar value,
while parentheses do not. So when a parenthesized list is evaluated in
a scalar context, the comma is treated like C's comma operator, which
throws away the left argument, which is not what you want. See
perlref for more on this.
This warning will not be issued for numerical constants equal to 0 or 1
since they are often used in statements like
1 while sub_with_side_effects();
String constants that would normally evaluate to 0 or 1 are warned
about.
Useless use of a variable in void context at InsertRecord.cgi line 59 (#1)
Useless use of a variable in void context at InsertRecord.cgi line 60 (#1)
Use of uninitialized value in transliteration (tr///) at InsertRecord.cgi line
23 (#2)
(W uninitialized) An undefined value was used as if it were already
defined. It was interpreted as a "" or a 0, but maybe it was a mistake.
To suppress this warning assign a defined value to your variables.
To help you figure out what was undefined, perl will try to tell you the
name of the variable (if any) that was undefined. In some cases it cannot
do this, so it also tells you what operation you used the undefined value
in. Note, however, that perl optimizes your program and the operation
displayed in the warning may not necessarily appear literally in your
program. For example, "that $foo" is usually optimized into "that "
. $foo, and the warning will refer to the concatenation (.) operator,
even though there is no . in your program.
Use of uninitialized value $ENV{"REQUEST_METHOD"} in string eq at
InsertRecord.cgi line 24 (#2)
Use of uninitialized value $buffer in split at InsertRecord.cgi line 29 (#2)
Location: http://.......:81/cgi-bin/showdata.cgi
Press any key to continue . . .
***********END***********************
What is the issue?
When I was editing your code so that it was more readable, I stumbled upon what I assume is the solution:
You are using $name when inserting into the database, but you use $first_name when getting the value $FORM{name}. So since you used $name above, it has the value of the last name used, whatever that might be. The relevant code snippets:
($name, $value) = split(/=/, $pair);
...
$FORM{$name} = $value;
...
my $first_name = $FORM{name};
...
$statement->execute($address,$age,$city,$name,$occupation)
# ^^^^^--- should be $first_name
Your problem would have been solved if you had used proper scope on your variables, namely something like this:
foreach my $pair (#pairs) {
my ($name, $value) = split(/=/, $pair);
$value =~ tr/+/ /;
$value =~ s/%(..)/pack("C", hex($1))/eg;
$FORM{$name} = $value;
}
Then when you later would try to use $name, you would get the error
Global variable "$name" requires explicit package name ...
Which would alert you to your mistake and save you hours in debugging time. When you declare variables at the top of the script, instead of in the smallest possible scope, you effectively disable the protection that use strict 'vars' offers. So don't do that.
Also, you should probably use the CGI module instead of trying to handle it manually. It will make things easier, and safer. Don't forget to perform sanity checks on your data to prevent database injection attacks.
Your script when cleaned up and properly formatted looks like this.
What happens when you replace your code with this:
#!"C:\xampp\perl\bin\perl.exe"
use strict;
use warnings;
use diagnostics;
use DBI;
use CGI qw[param redirect];
my $driver = "mysql";
my $database = "mysql";
my $dsn = "DBI:$driver:database=$database";
my $userid = "root";
my $password = "password";
my $dbh = DBI->connect("dbi:mysql:dbname=mysql", "root", "password",
{ AutoCommit => 0,RaiseError => 1}, )
or die "Couldn't connect to database: ", $DBI::errstr;
my $query = "insert into userrecords(Address,Age,City,Name,Occupation)
values (?, ?, ?, ?, ?) ";
my $statement = $dbh->prepare($query)
or die "Couldn't connect to database: " , $DBI::errstr;
$statement->execute(param('address'), param('age'), param('city'),
param('name'), param('occupation'))
or die "Couldn't connect to database: " , $DBI::errstr;
$dbh->disconnect();
my $URL = "http://.....:81/cgi-bin/showdata.cgi";
print redirect($URL);
I've basically made two changes:
Use the CGI.pm module to handle the CGI interaction (getting the parameters and printing the redirection header).
Fixed your "void context" errors by removing the misplaced parentheses in all of your calls to die.
I'm made no substantive changes to the code, but at least we now have a clean version to go with.
Update: D'oh. It's obvious now the code is cleaned up a bit. If you have "Autocommit" turned off, then you need to commit your changes. Add $dbh->commit between the calls to execute() and disconnect().
The warning comes from this:
or die ("Couldn't connect to database: ") , $DBI::errstr;
The , $DBI::errstr is outside of the die and nothing is done with it, thus being in void context. You want something like this:
or die ("Couldn't connect to database: $DBI::errstr");
Also, your form handling code has some issues. If you're writing CGI scripts, you may as well use the CGI module. Here's a quick cleanup of your code:
#!"C:\xampp\perl\bin\perl.exe"
use diagnostics;
use CGI ':standard';
use DBI;
use strict;
use warnings;
my $driver = "mysql";
my $database = "mysql";
my $dsn = "DBI:$driver:database=$database";
my $userid = "root";
my $password = "password";
my $name = param('name');
my $address = param('address');
my $city = param('city');
my $occupation = param('occupation');
my $age = param('age');
my $dbh = DBI->connect( $dsn, $userid, $password,
{ AutoCommit => 1, RaiseError => 1 },
) or die("Couldn't connect to database: $DBI::errstr");
my $query = <<'END';
INSERT INTO userrecords(Address,Age,City,Name,Occupation)
VALUES ( ?, ?, ?, ?, ?)
END
my $statement = $dbh->prepare($query);
$statement->execute( $address, $age, $city, $name, $occupation );
$dbh->disconnect();
my $URL = "http://.....:81/cgi-bin/showdata.cgi";
print "Location: $URL\n\n";
Note that I've removed many or die statements because you already have RaiseError set to a true value.
For simplicity's sake, I've also (reluctantly) turned on AutoCommit.
I am relatively new to perl and this forum. I am trying to use perl DBI for mySql LOAD DATA INFILE statement to upload a csv file to a mySQL database. However, the execute statement returns an undef value. However if i use a SELECT or DESC statement, it works fine. I suspect that the single quotes and braces in the query is causing the error but don't know how to debug.
#!/usr/bin/perl -w
use strict;
use warnings;
use File::Basename;
use DBI;
use DBD::mySQL;
my $data_path="D:\\NickD\\Project\\StockData\\";
my $db = "TestMMDB";
my $user = "user";
my $pass ="pass";
my $host = "localhost";
my $query ="";
my #row;
my #files = glob("$data_path*.csv");
DBI->trace(1);
my $dbh = DBI->connect("dbi:mysql:$db:$host",$user,$pass);
foreach my $file(#files){
my $filename = basename($file);
my ($db_table,$date) = split("_",$filename);
$query = q{LOAD DATA INFILE ? INTO TABLE ? FIELDS TERMINATED BY ',' (Date,Symbol,Open,High,Low,Close,Volume)};
my $sqlQuery = $dbh->prepare($query);
my $rv = $sqlQuery->execute($file,$db.".".$db_table) or die "Oops!: Can't execute the query :".$sqlQuery->errstr;
while (#row = $sqlQuery->fetchrow_array()) {
print "#row\n";
}
}
my $rc = $dbh->disconnect();
exit(0);
All help will be greatly appreciated.