I created a Stored Procedure to calculate how many hours was during day
(6:00-18:00), evening (18:00-22:00) and night (22:00-6:00 actually:
0:00-6:00 and 22:00-24:00).
this is meant to be used with view v_toopaev from my previous post:
BEGIN(algus) and END(lopp) are on the same date.

Problem is that this procedure returns 0 (minutes) for all of those.
However same logic used in Delphi procedure works fine.
What may be wrong here? (variable names are in Estonian, comment is the
meaning in Eglish)


CREATE PROCEDURE SP_TOOPAEV_TUNDE (
ALATES TIMESTAMP, /* beginning time*/
KUNI TIMESTAMP /* end time*/
) RETURNS (
TOOTATUD_OOSEL INTEGER, /* WORKED DURING NIGHT */
TOOTATUD_PAEVAL INTEGER, /* WORKED DURING DAY */
TOOTATUD_OHTUL INTEGER /* WORKED DURING EVENING */
) AS

DECLARE VARIABLE paevane_algus Date; /* daily hour start */
DECLARE VARIABLE ohtune_algus Date; /* evening hour start */
DECLARE VARIABLE oine_algus Date; /* nightly hour start */
DECLARE VARIABLE keskoo Date; /* midnight */

BEGIN


/* daily hour start */
select
CAST( ( extract(day from :alates)||'.'||extract(month from
:alates)||'.'||extract(year from :alates) ||' 6:00:00' ) as date)
from rdb$database into :paevane_algus;


/* evening hour start */
select
CAST( ( extract(day from :alates)||'.'||extract(month from
:alates)||'.'||extract(year from :alates) ||' 18:00:00' ) as date)
from rdb$database
into :ohtune_algus;

/* nightly hour start */
select
CAST( ( extract(day from :alates)||'.'||extract(month from
:alates)||'.'||extract(year from :alates) ||' 22:00:00' ) as date)
from rdb$database
into :oine_algus;

/* midnight */
select
CAST( ( extract(day from :alates)||'.'||extract(month from
:alates)||'.'||extract(year from :alates) ) as date)+1 from rdb$database
into :keskoo;

/* nightly hours in the morning */
if (alates<=paevane_algus) then
begin
if (kuni>=paevane_algus) then
tootatud_oosel=paevane_algus-alates;

if (kuni<paevane_algus) then
tootatud_oosel=kuni-alates;

end


/* nightly hours in the evening */
if (kuni<=keskoo) then
begin
if (alates>=oine_algus) then
tootatud_oosel=tootatud_oosel+(kuni-alates);

if (alates<oine_algus) then
tootatud_oosel=tootatud_oosel+(kuni-oine_algus);
end

if (kuni>oine_algus) then
begin
if (alates>=oine_algus) then
tootatud_oosel=tootatud_oosel+(keskoo-alates);
if (alates<oine_algus) then
tootatud_oosel=tootatud_oosel+(keskoo-oine_algus);
end

tootatud_oosel=tootatud_oosel*24*60;


/* hours during the day */
if (kuni<=ohtune_algus) then
begin
if (alates>=paevane_algus) then
tootatud_paeval=kuni-alates;
if (alates<paevane_algus) then
tootatud_paeval=kuni-paevane_algus;
end

if (kuni>ohtune_algus) then
begin
if (alates>=paevane_algus) then
tootatud_paeval=ohtune_algus-alates;
if (alates<paevane_algus) then
tootatud_paeval=ohtune_algus-paevane_algus;
end
tootatud_paeval=tootatud_paeval*24*60;

/* hours during evening */

if (kuni<=oine_algus) then
begin
if (alates>=ohtune_algus) then
tootatud_ohtul=kuni-alates;
if (alates<ohtune_algus) then
tootatud_ohtul=kuni-ohtune_algus;
end

if (kuni>oine_algus) then
begin
if (alates>=ohtune_algus) then
tootatud_ohtul=oine_algus-alates;
if (alates<ohtune_algus) then
tootatud_ohtul=oine_algus-ohtune_algus;
end
tootatud_ohtul=tootatud_ohtul*24*60;


suspend;
END