How to sort text in sqlite3 with specified locale?
SQLite supports integration with ICU. According to the Readme file,
sqlite/ext/icu/README.txt
the sqlite/ext/icu/
directory contains source code for the SQLite "ICU" extension, an
integration of the "International Components for Unicode" library with SQLite.
1. Features
1.1 SQL Scalars upper() and lower()
1.2 Unicode Aware LIKE Operator
1.3 ICU Collation Sequences
1.4 SQL REGEXP Operator
If you can't afford to compile the ICU extension you can have a UDF do the same. In PHP/PDO:
$pdo->sqliteCreateFunction('locale',
function ($data, $locale = 'root')
{
static $collators = array();
if (isset($collators[$locale]) !== true)
{
$collators[$locale] = new \Collator($locale);
}
return $collators[$locale]->getSortKey($data);
}
);
Example usage:
SELECT * FROM "table" ORDER BY locale("column", 'pt_PT');
I don't expect this approach to be as efficient as the native extension but it is surely more portable.
I accepted Doug Currie answer, but I want to add some "algorithm" how to do it, because sqlite3 documentation is very strange (at least for me).
Ok, we have working sqlite3 and now:
Download ICU extension for sqlite
Compile it:
gcc -shared icu.c `icu-config --ldflags` -o libSqliteIcu.so
It is for Linux. I also needed to install additional ICU development package:
sudo apt-get install libicu-dev
I'm working on 64 bit architecture and I get error with
__relocation R_X86_64_32S__
(whatever it means :). GCC suggested adding-fPIC
to compile options and it helped.Run sqlite3. We can load extension with command:
.load './libSqliteIcu.so'
Assuming that it is in the current directory, we can also specify whole path.
Create new collation:
SELECT icu_load_collation('pl_PL', 'POLISH');
The first parameter is desired locale and the second is it's (it can be whatever).
Now we can sort data with our new locale:
SELECT * FROM some_table ORDER BY name COLLATE POLISH;
And it is case insensitive!