QSqlQuery query(db);
qDebug() << "load extension res = " << query.exec(".load 'libSqliteIcu.so'; ");
qDebug() << "error = " << query.lastError().text();
qDebug() << "load collation res = " << query.exec("SELECT icu_load_collation('ru_RU', 'RUSSIAN')");
qDebug() << "error = " << query.lastError().text();

QSqlDatabase db = ...;
 QVariant v = db.driver()->handle();
 if (v.isValid() && qstrcmp(v.typeName(), "sqlite3*")==0) {
     // v.data() returns a pointer to the handle
     sqlite3 *handle = *static_cast<sqlite3 **>(v.data());
     if (handle != 0) { // check that it is not NULL
         ...
     }
 }

if( c=='l' && strncmp(azArg[0], "load", n)==0 && nArg>=2 ){
    const char *zFile, *zProc;
    char *zErrMsg = 0;
    zFile = azArg[1];
    zProc = nArg>=3 ? azArg[2] : 0;
    open_db(p);
    rc = sqlite3_load_extension(p->db, zFile, zProc, &zErrMsg);
    if( rc!=SQLITE_OK ){
      fprintf(stderr, "Error: %s\n", zErrMsg);
      sqlite3_free(zErrMsg);
      rc = 1;
    }
  }

- libsqlite3-dev
- sqlite3-0-dbg (необязательно)

wget www.sqlite.org/cvstrac/getfile?f=sqlite/ext/icu/icu.c -O icu.c

gcc -shared icu.c `icu-config --ldflags` -o libSqliteIcu.so

gcc -shared icu.c `icu-config --ldflags` -fPIC -o libSqliteIcu.so

...
LIBS += -lsqlite3
...

...
#include <sqlite3ext.h>
...
/*
После того как базу данных открыли пишем
*/
QVariant v = db.driver()->handle();
if (v.isValid() && qstrcmp(v.typeName(), "sqlite3*")==0) {
  sqlite3 *handle = *static_cast<sqlite3 **>(v.data());
  if (handle != 0) { // check that it is not NULL
    int res = sqlite3_enable_load_extension(handle,1);
    if (res == SQLITE_OK)
    {
      res = sqlite3_load_extension(handle,"libSqliteIcu.so",0,0);
      if (res == SQLITE_OK)
        qDebug() << "Sqlite3 load ICU extension sucessfully";
      else
        qDebug() <<  "Sqlite3 load ICU extension fail";
    }
  else
    qDebug() << "Sqlite3 enable load extension fail";
    }
}
...