вот описание этого remember, но всеравно не понятно чем оно отличается от обычного update set cnt=cnt+1 where ....

/*
** 2016-08-09
**
** The author disclaims copyright to this source code.  In place of
** a legal notice, here is a blessing:
**
**    May you do good and not evil.
**    May you find forgiveness for yourself and forgive others.
**    May you share freely, never taking more than you give.
**
*************************************************************************
**
** This file demonstrates how to create an SQL function that is a pass-through
** for integer values (it returns a copy of its argument) but also saves the
** value that is passed through into a C-language variable.  The address of
** the C-language variable is supplied as the second argument.
**
** This allows, for example, a counter to incremented and the original
** value retrieved, atomically, using a single statement:
**
**    UPDATE counterTab SET cnt=remember(cnt,$PTR)+1 WHERE id=$ID
**
** Prepare the above statement once.  Then to use it, bind the address
** of the output variable to $PTR and the id of the counter to $ID and
** run the prepared statement.
**
** One can imagine doing similar things with floating-point values and
** strings, but this demonstration extension will stick to using just
** integers.
*/