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Displaying posts with tag: SQLite (reset)
Sudoku Recursive Common Table Expression Solver

In this blog post, we’ll look at a solving Sudoku using MySQL 8.0 recursive common table expression.

Vadim was recently having a little Saturday morning fun solving Sudoku using MySQL 8. The whole idea comes from SQLite, where Richard Hipp has come up with some outlandish recursive query examplesWITH clause.

The SQLite query:

WITH RECURSIVE
 input(sud) AS (
   VALUES('53..7....6..195....98....6.8...6...34..8.3..17...2...6.6....28....419..5....8..79')
 ),
 digits(z, lp) AS (
   VALUES('1', 1)
   UNION ALL SELECT
   CAST(lp+1 AS TEXT), lp+1 FROM digits WHERE lp<9
 ),
 x(s, ind) AS (
   SELECT sud, instr(sud, '.') FROM input
   UNION ALL …
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Using Active Record migrations beyond SQLite

SQLite is really a good tool to set up quick proof of concepts and small applications; however it’s not the most robust solution on the market for working with relational databases. In the open source community two databases take the top of the list: PostgreSQL and MySQL.

I did a small project for my studies. I was using SQLite as I didn’t need much out of it. Curious, I decided to see how the application would behave on other databases and decided to try PostgreSQL and MySQL. I had two problems to solve, and this post is about the first one: how to deal with the migrations. They were as follows:

Active Record automatically put the field id in all of its tables, that’s why it is omitted on the migrations.

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ProxySQL Admin Interface Is Not Your Typical MySQL Server!

In this blog post, I’ll look at how ProxySQL Admin behaves in some unusual and unexpected ways from a MySQL perspective.

ProxySQL allows you to connect to its admin interface using the MySQL protocol and use familiar tools, like the MySQL command line client, to manage its configuration as a set of configuration tables. This ability may trick you into thinking that you’re working with a stripped-down MySQL server – and expect it to behave like MySQL. 

It would be a mistake to think this! In fact, ProxySQL embeds the SQLite database to store its configuration. As such, it behaves much closer to SQLite!

Below, I’ll show you a few things that confused me at first. All of these are as of ProxySQL 1.3.6 (in case behavior changes in the future).

Fake support for Use command

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Some observations on MySQL to sqlite migration & compatibility

I'm experimenting with sqlite as backend database for orchestrator. While orchestrator manages MySQL replication topologies, it also uses MySQL as backend. For some deployments, and I'm looking into such one, having MySQL as backend is a considerable overhead.

This sent me to the route of looking into a self contained orchestrator binary + backend DB. I would have orchestrator spawn up its own backend database instead of connecting to an external one.

Why even relational?

Can't orchestrator just use a key-value backend?

Maybe it could. But frankly I enjoy the power of relational databases, and the versatility they offer has proven itself multiple times with orchestrator, being able to answer …

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When simple SQL can be complex

I think SQL is a very simple language, but ofcourse I'm biased.

But even a simple statement might have more complexity to it than you might think.

Do you know what the result is of this statement?

SELECT FALSE = FALSE = TRUE;

scroll down for the answer.



























The answer is: it depends.

You might expect it to return false because the 3 items in the comparison are not equal. But that's not the case.

In PostgreSQL this is the result:

postgres=# SELECT FALSE = FALSE = TRUE;
?column?
----------
t
(1 row)

So it compares FALSE against FALSE, which results in TRUE …

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SQLite vs MySQL

Today I got asked from a friend about the differences between SQLite and MySQL and in which cases it is better to use the first or the latter one. You can’t really compare these two, I will try to explain why this is the case and when it is better to use the first or the latter.

SQLite is a single-file based database which is useful for testing and for embedding in applications. This means that all the information is stored in a single file on a file system and you use a SQLite library to open this file to read and write your data.

MySQL is a database server which got different forms to store its data (engines) and will server the data to request comming from applications who connect to it.

SQLite:

  • Fast setup. You only need to include a library into your app.
  • Embedded. No need to think about …
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Simple MySQL: Converting ANSI SQL to SQLite3

I was digging through some old project code and found this script. Sometimes one finds oneself in an odd situation and needs to convert regular SQL, say from a MySQL database dump, into SQLite3 format. There’s not too much else to say, but here is a script that helps with the process. It can likely be improved but this handles the items that came up during conversion on initial runs.

#!/bin/sh
####
# NAME: convert-mysql-to-sqlite3.sh
# AUTHOR: Matt Reid
# DATE: 2011-03-22
# LICENSE: BSD
####
if [ "x$1" == "x" ]; then
   echo "Usage: $0 "
   exit 
fi 
cat $1 |
grep -v ' KEY "' |   
grep -v ' UNIQUE KEY "' |
grep -v ' PRIMARY KEY ' |
sed '/^SET/d' |          
sed 's/ unsigned / /g' | 
sed 's/ auto_increment/ primary key autoincrement/g' |
sed 's/ smallint([0-9]*) / integer /g' | 
sed 's/ tinyint([0-9]*) / integer /g' |  
sed 's/ int([0-9]*) / integer /g' |      
sed 's/ character set [^ ]* / /g' |      
sed 's/ enum([^)]*) / varchar(255) /g' | 
sed 's/ on …
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NIST::NVD::Store::SQLite3 1.00.00

It’s been released. Use this with NIST::NVD 1.00.00 and you will be able to perform immediate look-ups of CVE and CWE data given a CPE URN. For instance:

cjac@foxtrot:/usr/src/git/f5/NIST-NVD-Store-SQLite3$ perl Makefile.PL ; make ; make test ; cjac@foxtrot:/usr/src/git/f5/NIST-NVD-Store-SQLite3$ perl -MNIST::NVD::Query -MData::Dumper -e '
$q = NIST::NVD::Query->new(store    => q{SQLite3},database => q{t/data/nvdcve-2.0.db});
$cve_list = $q->cve_for_cpe( cpe => q{cpe:/a:microsoft:ie:7.0.5730.11} );
print Data::Dumper::Dumper { cve_list => $cve_list, first_cvss => $q->cve( cve_id => $cve_list->[0] )->{q{vuln:cvss}} }
'
$VAR1 = {
          'cve_list' => [
                          'CVE-2002-2435',
                          'CVE-2010-5071'
                        ],
          'first_cvss' => {
                            'cvss:base_metrics' => { …
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NIST::NVD CWE development – follow along

I’m in the process of getting the tests passing for the 0.03 release of NIST::NVD::Store::SQLite3 wherein our hero imports the CWE data and cross-indexes it with CVEs and CPEs.

Follow along and suggest some patches. I’m developing on Debian Wheezy, but I would very much like input from devs on other platforms.

http://git.colliertech.org/?p=NIST-NVD-Store-SQLite3.git;a=summary

cjac@foxtrot:/tmp$ time git clone http://git.colliertech.org/git/NIST-NVD-Store-SQLite3.git
Cloning into 'NIST-NVD-Store-SQLite3'...

real    0m32.757s
user    0m0.200s
sys     0m0.088s
cjac@foxtrot:/tmp$ ls NIST-NVD-Store-SQLite3/t/data/
cwec_v2.1.xml  nvdcve-2.0-test.xml

Publish your patches and I’ll fetch them, or you can submit them in udiff format and I’ll review/apply. Thanks for playing along!

[edit 20120216T1456 -0800] …

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NIST::NVD::Store::SQLite3

I published an SQLite3 storage back-end to NIST::NVD on the CPAN. It’s pretty quick. About as fast as the DB_File one, but without the down side of being tied to DB_File. It shouldn’t be too difficult to re-factor this code to any DBI-based database. MariaDB anyone?

I know it works on Debian. The nightly CPAN test results should come back shortly and I’ll find out how well it works on other platforms.

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