What is the best way to construct sql with various number of WHERE conditions ?
My solution looks ugly:
my ($where, #values);
if ($phone_number)
{
$where = 'AND pnone_number=?';
#values = ($from, $till, $phone_number);
}
else
{
$where = '';
#values = ($from, $till);
}
my $sql = 'SELECT * FROM calls WHERE time between ? AND ? '.$where.' ORDER BY time';
my $res = $dbh->selectall_arrayref($sql, undef, #values) or warn 'error';
How about:
my $where = '';
my #values = ( $from, $till );
if ( $phone_number ) {
$where = 'AND phone_number=?';
push #values, $phone_number;
}
That eliminates the need for your else clause.
You could also use something like SQL::Abstract.
use SQL::Abstract;
...
my ( $sql, #values ) = SQL::Abstract->new->select(
'calls', # table
'*', # columns
{ time => { '<=' => $till, '>' => $from }, # where clause
$phone_number ? ( phone_number => $phone_number ) : ( ),
},
'time' # order clause
);
1=1 is added for cases when $where would be epmty.
my $where = "AND time between ? AND ? ";
my #values = ($from, $till);
if ($phone_number) {
$where .= 'AND pnone_number=? ';
push #values, $phone_number;
}
my $sql = 'SELECT * FROM calls WHERE 1=1 $where ORDER BY time';
my $res = $dbh->selectall_arrayref($sql, undef, #values) or warn 'error';
Conditional list-include (aka "enterprise"):
my #values = ( $from,
$till,
( $phone_number ) x !! $phone_number,
);
my $sql = 'SELECT * FROM calls WHERE time between ? AND ? '
. 'AND phone_number=?' x !! $phone_number
. ' ORDER BY time';
Related
I have this raw sql statement which I am trying to execute through Zend_DB.
$sql = 'SELECT relocationaction.id, relocationaction.vehicle, relocationaction.start, relocationaction.end, relocationaction.return ' .
'FROM relocationaction,
(SELECT vehicle, MAX(end) AS maxend
FROM relocationaction
GROUP BY vehicle) AS co2
WHERE co2.vehicle = relocationaction.vehicle
AND(relocationaction.monitor = 1)
AND (relocationaction.return IS NULL)
AND (start <= ?)
AND relocationaction.end = co2.maxend';
I have found a possible solution using this type of notation, but it is rendered to a totally different and wrong sql statement with joins and strange table names.
$tbl = $this->getDbTable();
$select = $tbl->select()->setIntegrityCheck(false);
$subSelect = $select->from('relocationaction', array('vehicle', 'maxend' => 'MAX(relocationaction.end)'))
->group('vehicle');
$subSelectString = '(' . $subSelect->__toString() . ')';
$select ->from(
array('relocationaction'), array('id', 'date' => 'start', 'enddate' => 'end', 'return'),
array('co2' => $subSelectString)
)
->joinLeft('exhibitvehicle', 'exhibitvehicle.id = relocationaction.vehicle', array())
->where('co2.vehicle = relocationaction.vehicle')
->where('relocationaction.monitor = 1')
->where('relocationaction.return IS NULL')
->where('start <= ?', $start->get('yyyy-MM-dd'))
->where('relocationaction.end = co2.maxend');
Can anyone please give me a hint?
Thanks
Jesse
UPDATE
This is the result of the second expression (total rubbish)
SELECT `relocationaction`.`vehicle`,
MAX(relocationaction.end) AS `maxend`,
`relocationaction_2`.`id`,
`relocationaction_2`.`start` AS `date`,
`relocationaction_2`.`end` AS `enddate`,
`relocationaction_2`.`return`
FROM `relocationaction`
INNER JOIN `(
SELECT ``relocationaction``.``vehicle``,
MAX(relocationaction.end) AS ``maxend`` FROM ``relocationaction`` GROUP BY ``vehicle``)`.`relocationaction` AS `relocationaction_2`
LEFT JOIN `exhibitvehicle` ON exhibitvehicle.id = relocationaction.vehicle
WHERE (col2.vehicle = relocationaction.vehicle)
AND (relocationaction.monitor = 1)
AND (relocationaction.return IS NULL)
AND (start <= '2013-05-08')
AND (relocationaction.end = col2.maxend)
GROUP BY `vehicle`
If you use a string in from(), Zend_Db_Select will consider it to be a table name so it escapes it.
The solution is to wrap your subselect into a Zend_Db_Expr.
$tbl = $this->getDbTable();
$select = $tbl->select()->setIntegrityCheck(false);
$subSelect = $select->from('relocationaction', array('vehicle', 'maxend' => 'MAX(relocationaction.end)'))
->group('vehicle');
$subSelectString = '(' . $subSelect->__toString() . ')';
$select ->from(
array('relocationaction'), array('id', 'date' => 'start', 'enddate' => 'end', 'return'),
array('co2' => new Zend_Db_Expr($subSelectString))
)
->joinLeft('exhibitvehicle', 'exhibitvehicle.id = relocationaction.vehicle', array())
->where('co2.vehicle = relocationaction.vehicle')
->where('relocationaction.monitor = 1')
->where('relocationaction.return IS NULL')
->where('start <= ?', $start->get('yyyy-MM-dd'))
->where('relocationaction.end = co2.maxend');
Ok here we go. I tried hard to find a solution with Zend_Db_Table but failed big time. That's why I finally did it with PDO, as suggested by #user466764. Thanks for your help.
$tbl = $this->getDbTable();
$query = 'SELECT relocationaction.id,
relocationaction.vehicle,
relocationaction.start,
relocationaction.end,
relocationaction.return
FROM relocationaction
(SELECT vehicle, MAX(end) AS maxend
FROM relocationaction
GROUP BY vehicle) AS co2
WHERE co2.vehicle = relocationaction.vehicle
AND(relocationaction.monitor = 1)
AND (relocationaction.return IS NULL)
AND (start <= "' . $start->get('yyyy-MM-dd') . '")
AND relocationaction.end = co2.maxend';
$sth = $tbl->getAdapter()->prepare($query);
$sth->execute();
$entries = $sth->fetchAll();
When I fetch the data this way is it possible then to access the column names and the column types or do I need an explicit prepare to reach this?
use DBI;
my $dbh = DBI->connect( ... );
my $select = "...";
my #arguments = ( ... );
my $ref = $dbh->selectall_arrayref( $select, {}, #arguments, );
Update:
With prepare I would do it this way:
my $sth = $dbh->prepare( $select );
$sth->execute( #arguments );
my $col_names = $sth->{NAME};
my $col_types = $sth->{TYPE};
my $ref = $sth->fetchall_arrayref;
unshift #$ref, $col_names;
The best solution is to use prepare to get a statement handle, as you describe in the second part of your question. If you use selectall_hashref or selectall_arrayref, you don't get a statement handle, and have to query the column type information yourself via $dbh->column_info (docs):
my $sth = $dbh->column_info('','',$table,$column); # or $column='' for all
my $info = $sth->fetchall_arrayref({});
use Data::Dumper; print Dumper($info);
(specifically, the COLUMN_NAME and TYPE_NAME attributes).
However, this introduces a race condition if the table changes schema between the two queries.
Also, you may use selectall_arrayref with the Slice parameter to fetch all the columns into a hash ref, it needs no prepared statement and will return an array ref of the result set rows, with each rows columns the key's to a hash and the values are the column values. ie:
my $result = $dbh->selectall_arrayref( qq{
SELECT * FROM table WHERE condition = value
}, { Slice => {} }) or die "Error: ".$dbh->errstr;
$result = [
[0] = { column1 => 'column1Value', column2 => 'column2Value', etc...},
[1] = { column1 => 'column1Value', column2 => 'column2Value', etc...},
];
Making it easy to iterate over results.. ie:
for my $row ( #$results ){
print "$row->{column1Value}, $row->{column2Value}\n";
}
You can also specify which columns to extract but it's pretty useless due to the fact it's more efficient to do that in your SQL query syntax.
{ Slice => { column1Name => 1, column2Name => 1 } }
That would only return the values for column1Name and column2Name just like saying in your SQL:
SELECT column1Name, column2Name FROM table...
I have been trying to use sql NOW() function while I update a table. But nothing happens to that date field, I think DBI just ignores that value. Code is :
dbUpdate($id, (notes => 'This was an update', filesize => '100.505', dateEnd => 'NOW()'));
and the function is :
sub dbUpdate {
my $id = shift;
my %val_hash = #_;
my $table = 'backupjobs';
my #fields = keys %val_hash;
my #values = values %val_hash;
my $update_stmt = "UPDATE $table SET ";
my $count = 1;
foreach ( #fields ) {
$update_stmt .= "$_ = ? ";
$update_stmt .= ', ' if ($count != scalar #fields);
$count++;
}
$update_stmt .= " WHERE ID = ?";
print "update_stmt is : $update_stmt\n";
my $dbo = dbConnect();
my $sth = $dbo->prepare( $update_stmt );
$sth->execute( #values, $id ) or die "DB Update failed : $!\n";
$dbo->disconnect || die "Failed to disconnect\n";
return 1;
}#dbUpdate
As you can see this is a "dynamic" generation of the sql query and hence I dont know where an sql date function(like now()) come.
In the given example the sql query will be
UPDATE backupjobs SET filesize = ? , notes = ? , dateEnd = ? WHERE ID = ?
with param values
100.55, This was an update, NOW(), 7
But the date column still shows 0000-00-........
Any ideas how to fix this ?
I have been trying to use sql NOW() function while I update a table. But
nothing happens to that date field, I think DBI just ignores that
value.
No, it doesn't. But the DB thinks you are supplying a datetime or timestamp data type when you are in fact trying to add the string NOW(). That of course doesn't work. Unfortunately DBI cannot find that out for you. All it does is change ? into an escaped (via $dbh->quote()) version of the string it got.
There are several things you could do:
Supply a current timestamp string in the appropriate format instead of the string NOW().
If you have it available, you can use DateTime::Format::MySQL like this:
use DateTime::Format::MySQL;
dbUpdate(
$id,
(
notes => 'This was an update',
filesize => '100.505',
dateEnd => DateTime::Format::MySQL->format_datetime(DateTime->now),
)
);
If not, just use DateTime or Time::Piece.
use DateTime;
my $now = DateTime->now->datetime;
$now =~ y/T/ /;
dbUpdate(
$id,
(notes => 'This was an update', filesize => '100.505', dateEnd => $now));
Tell your dbUpdate function to look for things like NOW() and react accordingly.
You can do something like this. But there are better ways to code this. You should also consider that there is e.g. CURRENT_TIMESTAMP() as well.
sub dbUpdate {
my $id = shift;
my %val_hash = #_;
my $table = 'backupjobs';
my $update_stmt = "UPDATE $table SET ";
# Check for the NOW() value
# This could be done with others too
foreach ( keys %val_hash ) {
if ($val_hash{$_} =~ m/^NOW\(\)$/i) {
$update_stmt .= "$_ = NOW()";
$update_stmt .= ', ' if scalar keys %val_hash > 1;
delete $val_hash{$_};
}
}
# Put everything together, join keeps track of the trailing comma
$update_stmt .= join(', ', map { "$_=?" } keys %val_hash );
$update_stmt .= " WHERE ID = ?";
say "update_stmt is : $update_stmt";
say "values are: ", join(', ', values %val_hash);
my $dbo = dbConnect();
my $sth = $dbo->prepare( $update_stmt );
$sth->execute( values %val_hash, $id ) or die "DB Update failed : $!\n";
$dbo->disconnect || die "Failed to disconnect\n";
return 1;
}
Write your queries yourself.
You're probably not going to do it and I'll not add an example since you know how to do it anyway.
Here's something else: Is this the only thing you do with your database while your program runs? It is not wise to connect and disconnect the database every time you make a query. It would be better for performance to connect the database once you need it (or at the beginning of the program, if you always use it) and just use this dbh/dbo everywhere. It saves a lot of time (and code).
Sorry but you can't use NOW() as an interpolated value like that.
when a ? is used in an SQL statement, the corresponding value is (via some mechanism or other) passed to the database escaped, so whatever value is interpreted as a string, not as SQL. So you are in effect attempting to use the string 'NOW()' as a date value, not the function NOW().
To use NOW() as a function, you will have to insert it into the SQL itself rather than pass it as a bound value. This means you will either have to use a hack of your dbupdate function or write a new one, or obtain the time as a string in perl and pass the resulting string the dbupdate.
#!/usr/bin/env perl
use warnings;
use 5.012;
use DBI;
my $dsn = "DBI:Proxy:hostname=horst;port=2000;dsn=DBI:ODBC:db1.mdb";
my $dbh = DBI->connect( $dsn, undef, undef ) or die $DBI::errstr;
$dbh->{RaiseError} = 1;
$dbh->{PrintError} = 0;
my $my_table = 'my_table';
eval{ $dbh->do( "DROP TABLE $my_table" ) };
$dbh->do( "CREATE TABLE $my_table" );
my $ref = [ qw( 1 2 ) ];
for my $col ( 'col_1', 'col_2', 'col_3' ) {
my $add = "$col INT";
$dbh->do( "ALTER TABLE $my_table ADD $add" );
my $sql = "INSERT INTO $my_table ( $col ) VALUES( ? )";
my $sth = $dbh->prepare( $sql );
$sth->bind_param_array( 1, $ref );
$sth->execute_array( { ArrayTupleStatus => \my #tuple_status } );
}
my $sth = $dbh->prepare( "SELECT * FROM $my_table" );
$sth->execute();
$sth->dump_results();
$dbh->disconnect;
This script outputs:
'1', undef, undef
'2', undef, undef
undef, '1', undef
undef, '2', undef
undef, undef, '1'
undef, undef, '2'
6 rows
How do I have to change this script to get this output:
'1', '1', '1'
'2', '2', '2'
2 rows
Do this in two steps:
Create the 3 columns
insert data in them
You prepare a SQL statement 3 times and execute twice for values 1,2 so you get 6 rows. I don't know how to answer your question of how do you change it to get 2 rows since we've no idea what you are trying to achieve. Without knowing what you are trying to achieve I'd be guessing but the following results in the output you wanted:
my $ref = [ qw( 1 2 ) ];
for my $col ( 'col_1', 'col_2', 'col_3' ) {
my $add = "$col INT";
$dbh->do( "ALTER TABLE $my_table ADD $add" );
}
$sql = "INSERT INTO $my_table ( col_1, col_2, col_3 ) VALUES( ?,?,? )";
my $sth = $dbh->prepare( $sql );
$sth->bind_param_array( 1, $ref );
$sth->bind_param_array( 2, $ref );
$sth->bind_param_array( 3, $ref );
$sth->execute_array( { ArrayTupleStatus => \my #tuple_status } );
In this script I have problems with file-name-extensions:
if I use /home/mm/test_x it works, with file named /home/mm/test_x.csv it doesn't:
#!/usr/bin/env perl
use warnings; use strict;
use 5.012;
use DBI;
my $table_1 = '/home/mm/test_1.csv';
my $table_2 = '/home/mm/test_2.csv';
#$table_1 = '/home/mm/test_1';
#$table_2 = '/home/mm/test_2';
my $dbh = DBI->connect( "DBI:CSV:" );
$dbh->{RaiseError} = 1;
$table_1 = $dbh->quote_identifier( $table_1 );
$table_2 = $dbh->quote_identifier( $table_2 );
my $sth = $dbh->prepare( "SELECT a.id, a.name, b.city FROM $table_1 AS a NATURAL JOIN $table_2 AS b" );
$sth->execute;
$sth->dump_results;
$dbh->disconnect;
Output with file-name-extention:
DBD::CSV::st execute failed:
Execution ERROR: No such column '"/home/mm/test_1.csv".id' called from /usr/local/lib/perl5/site_perl/5.12.0/x86_64-linux/DBD/File.pm at 570.
Output without file-name-extension:
'1', 'Brown', 'Laramie'
'2', 'Smith', 'Watertown'
2 rows
Is this a bug?
cat test_1.csv
id,name
1,Brown
2,Smith
5,Green
cat test_2.csv
id,city
1,Laramie
2,Watertown
8,Springville
DBD::CSV provides a way to map the table names you use in your queries to filenames. The same mechanism is used to set up per-file attributes like line ending, field separator etc. look for 'csv_tables' in the DBD::CSV documentation.
#!/usr/bin/env perl
use warnings;
use strict;
use DBI;
my $dbh = DBI->connect("DBI:CSV:f_dir=/home/mm", { RaiseError => 1 });
$dbh->{csv_tables}->{table_1} = {
'file' => 'test_1.csv',
'eol' => "\n",
};
$dbh->{csv_tables}->{table_2} = {
'file' => 'test_2.csv',
'eol' => "\n",
};
my $sth = $dbh->prepare( "SELECT a.id, a.name, b.city FROM table_1 AS a NATURAL JOIN table_2 AS b" );
$sth->execute();
$sth->dump_results();
$dbh->disconnect();
In my case I had to specify a line ending character, because I created the CSV files in vi so they ended up with Unix line endings whereas DBD::CSV assumes DOS/Windows line-endings regardless of the platform the script is run on.
I looks like even this works:
#!/usr/bin/env perl
use warnings; use strict;
use 5.012;
use DBI;
my $dbh = DBI->connect("DBI:CSV:f_dir=/home/mm/Dokumente", undef, undef, { RaiseError => 1, });
my $table = 'new.csv';
$dbh->do( "DROP TABLE IF EXISTS $table" );
$dbh->do( "CREATE TABLE $table ( id INT, name CHAR(64), city CHAR(64) )" );
my $sth_new = $dbh->prepare( "INSERT INTO $table( id, name, city ) VALUES ( ?, ?, ? )" );
$dbh->{csv_tables}->{table_1} = { 'file' => '/tmp/test_1.csv', 'eol' => "\n", };
$dbh->{csv_tables}->{table_2} = { 'file' => '/tmp/test_2.csv', 'eol' => "\n", };
my $sth_old = $dbh->prepare( "SELECT a.id, a.name, b.city FROM table_1 AS a NATURAL JOIN table_2 AS b" );
$sth_old->execute();
while ( my $hash_ref = $sth_old->fetchrow_hashref() ) {
state $count = 1;
$sth_new->execute( $count++, $hash_ref->{'a.name'}, $hash_ref->{'b.city'} );
}
$dbh->disconnect();
I think you might want to take a look at the f_ext and f_dir attributes. You can then class your table names as "test_1" and "test_2" without the csv but the files used will be test_1.csv and test_2.csv. The problem with a dot in the table name is a dot is usually used for separating the schema from the table name (see f_schema).