9 More Discussions You Might Find Interesting
1. UNIX for Beginners Questions & Answers
Hi there,
I have multiple rows of data.
For example:
S/N | Name| Age
I would like to store them into sqlite database after doing some grepping in CSV and output them into console/html format.
Will it be possible? (1 Reply)
Discussion started by: alvinoo
1 Replies
2. Shell Programming and Scripting
Okay, so this one is a bit above my knowledge level so I'm hoping for some pointers.
Here's the scenario:
I have a backup system on my network that makes single file images of the machines it's backing up and uses an sqlite database to keep track of everything. As is pretty typical with... (2 Replies)
Discussion started by: NyxPDX
2 Replies
3. UNIX and Linux Applications
Hello,
I'm not sure this is quite the right place, but there do seem to be allot of posts with folks using ruby to play nicely with databases so I thought I would give it a go.
I am starting a long process of developing a database application bases on SQLite and ruby. This will run on various... (1 Reply)
Discussion started by: LMHmedchem
1 Replies
4. Shell Programming and Scripting
hlow all
i have file like this :
BDG0100.2011091620162100CF5341.DAT
BDG0100.2011091720175500CF5342.DAT
BDG0100.2011091820192900CF5343.DAT
BDG0100.2011091920210600CF5344.DAT
but now i want make file like this
20110916.DAT
20110919.DAT
20110918.DAT
20110919.DAT
so what i can do that... (3 Replies)
Discussion started by: zvtral
3 Replies
5. Shell Programming and Scripting
I have several bash scripts that write to an SQLite3 database at the same time. At some occasion the database returns: SQL error: database is locked.
How would be the best way, to make a process to wait until the data base is 'free' again. I tried:
sqlite3 test.db ".timeout 1000; update....."... (2 Replies)
Discussion started by: creamcheese
2 Replies
6. Shell Programming and Scripting
Hi everyone,
I have a requirement that requires me to fill an sqlite database with 100,000 entries (no duplicates).
I will start out by giving the command that will insert the values necessary to populate the database:
# sqlite /var/local/database/dblist "insert into list... (2 Replies)
Discussion started by: ogoy
2 Replies
7. Shell Programming and Scripting
Hello All,
I am trying to write a Perl script that is using 'SQLite' as the application needs a very light weight Database. I wanted to know how to catch exceptions when I run queries in SQLite. Without this the Perl script comes to a halt everytime an exception occurs. Please help.
Regards,... (4 Replies)
Discussion started by: garric
4 Replies
8. HP-UX
Hi everybody,
We have a cgi application which accesses sqlite database. It works fine in Linux environment but the same code doesn't enter data into the database when done in HP-UX environment. Should the codes vary depending on whether it is Linux or HP-UX.
Regards
Ruma (1 Reply)
Discussion started by: perlprg
1 Replies
9. UNIX for Dummies Questions & Answers
i'm on freebsd 5.2.1, and from a fresh installation i've used pkg_add for the latest ported version of apache, as well as installing php 5. supposedly php5 comes with native support for sqlite (in the binary package), and this is what i added.
i am trying to install a site engine (the 'gyrator'... (0 Replies)
Discussion started by: brandan
0 Replies
DBD::SQLite2(3pm) User Contributed Perl Documentation DBD::SQLite2(3pm)
NAME
DBD::SQLite2 - Self Contained RDBMS in a DBI Driver (sqlite 2.x)
SYNOPSIS
use DBI;
my $dbh = DBI->connect("dbi:SQLite2:dbname=dbfile","","");
DESCRIPTION
SQLite is a public domain RDBMS database engine that you can find at http://www.hwaci.com/sw/sqlite/.
Rather than ask you to install SQLite first, because SQLite is public domain, DBD::SQLite2 includes the entire thing in the distribution.
So in order to get a fast transaction capable RDBMS working for your perl project you simply have to install this module, and nothing else.
SQLite supports the following features:
Implements a large subset of SQL92
See http://www.hwaci.com/sw/sqlite/lang.html for details.
A complete DB in a single disk file
Everything for your database is stored in a single disk file, making it easier to move things around than with DBD::CSV.
Atomic commit and rollback
Yes, DBD::SQLite2 is small and light, but it supports full transactions!
Extensible
User-defined aggregate or regular functions can be registered with the SQL parser.
There's lots more to it, so please refer to the docs on the SQLite web page, listed above, for SQL details. Also refer to DBI for details
on how to use DBI itself.
CONFORMANCE WITH DBI SPECIFICATION
The API works like every DBI module does. Please see DBI for more details about core features.
Currently many statement attributes are not implemented or are limited by the typeless nature of the SQLite database.
DRIVER PRIVATE ATTRIBUTES
Database Handle Attributes
sqlite_version
Returns the version of the SQLite library which DBD::SQLite2 is using, e.g., "2.8.0".
sqlite_encoding
Returns either "UTF-8" or "iso8859" to indicate how the SQLite library was compiled.
sqlite_handle_binary_nulls
Set this attribute to 1 to transparently handle binary nulls in quoted and returned data.
NOTE: This will cause all backslash characters ("") to be doubled up in all columns regardless of whether or not they contain binary
data or not. This may break your database if you use it from another application. This does not use the built in sqlite_encode_binary
and sqlite_decode_binary functions, which may be considered a bug.
DRIVER PRIVATE METHODS
$dbh->func('last_insert_rowid')
This method returns the last inserted rowid. If you specify an INTEGER PRIMARY KEY as the first column in your table, that is the column
that is returned. Otherwise, it is the hidden ROWID column. See the sqlite docs for details.
$dbh->func( $name, $argc, $func_ref, "create_function" )
This method will register a new function which will be useable in SQL query. The method's parameters are:
$name
The name of the function. This is the name of the function as it will be used from SQL.
$argc
The number of arguments taken by the function. If this number is -1, the function can take any number of arguments.
$func_ref
This should be a reference to the function's implementation.
For example, here is how to define a now() function which returns the current number of seconds since the epoch:
$dbh->func( 'now', 0, sub { return time }, 'create_function' );
After this, it could be use from SQL as:
INSERT INTO mytable ( now() );
$dbh->func( $name, $argc, $pkg, 'create_aggregate' )
This method will register a new aggregate function which can then used from SQL. The method's parameters are:
$name
The name of the aggregate function, this is the name under which the function will be available from SQL.
$argc
This is an integer which tells the SQL parser how many arguments the function takes. If that number is -1, the function can take any
number of arguments.
$pkg
This is the package which implements the aggregator interface.
The aggregator interface consists of defining three methods:
new()
This method will be called once to create an object which should be used to aggregate the rows in a particular group. The step() and
finalize() methods will be called upon the reference return by the method.
step(@_)
This method will be called once for each rows in the aggregate.
finalize()
This method will be called once all rows in the aggregate were processed and it should return the aggregate function's result. When
there is no rows in the aggregate, finalize() will be called right after new().
Here is a simple aggregate function which returns the variance (example adapted from pysqlite):
package variance;
sub new { bless [], shift; }
sub step {
my ( $self, $value ) = @_;
push @$self, $value;
}
sub finalize {
my $self = $_[0];
my $n = @$self;
# Variance is NULL unless there is more than one row
return undef unless $n || $n == 1;
my $mu = 0;
foreach my $v ( @$self ) {
$mu += $v;
}
$mu /= $n;
my $sigma = 0;
foreach my $v ( @$self ) {
$sigma += ($x - $mu)**2;
}
$sigma = $sigma / ($n - 1);
return $sigma;
}
$dbh->func( "variance", 1, 'variance', "create_aggregate" );
The aggregate function can then be used as:
SELECT group_name, variance(score) FROM results
GROUP BY group_name;
NOTES
To access the database from the command line, try using dbish which comes with the DBI module. Just type:
dbish dbi:SQLite:foo.db
On the command line to access the file foo.db.
Alternatively you can install SQLite from the link above without conflicting with DBD::SQLite2 and use the supplied "sqlite" command line
tool.
PERFORMANCE
SQLite is fast, very fast. I recently processed my 72MB log file with it, inserting the data (400,000+ rows) by using transactions and only
committing every 1000 rows (otherwise the insertion is quite slow), and then performing queries on the data.
Queries like count(*) and avg(bytes) took fractions of a second to return, but what surprised me most of all was:
SELECT url, count(*) as count FROM access_log
GROUP BY url
ORDER BY count desc
LIMIT 20
To discover the top 20 hit URLs on the site (http://axkit.org), and it returned within 2 seconds. I'm seriously considering switching my
log analysis code to use this little speed demon!
Oh yeah, and that was with no indexes on the table, on a 400MHz PIII.
For best performance be sure to tune your hdparm settings if you are using linux. Also you might want to set:
PRAGMA default_synchronous = OFF
Which will prevent sqlite from doing fsync's when writing (which slows down non-transactional writes significantly) at the expense of some
peace of mind. Also try playing with the cache_size pragma.
BUGS
Likely to be many, please use http://rt.cpan.org/ for reporting bugs.
AUTHOR
Matt Sergeant, matt@sergeant.org
Perl extension functions contributed by Francis J. Lacoste <flacoste@logreport.org> and Wolfgang Sourdeau <wolfgang@logreport.org>
SEE ALSO
DBI.
perl v5.14.2 2004-09-10 DBD::SQLite2(3pm)