Create an entire timestamp in Firebird

Question

I need a timestamp as an integer (please DO NOT ask me why, I am completely concerned about this). The definition is the number of seconds after 01/01/1970, as usual.

What I have as the initial value is a string with the format

YYYYMMDDHHMMSS (e.g. 20140108154821)

I was able to create a regular timestamp

CAST(
(SUBSTRING ( t.thetime FROM 5 FOR 2 )||'/'||SUBSTRING ( t.thetime FROM 7 FOR 2 )||'/'||SUBSTRING ( t.thetime FROM 1 FOR 4 )||' ' ||SUBSTRING ( t.thetime FROM 9 FOR 2 )||':'||SUBSTRING ( t.thetime FROM 11 FOR 2 )||':'||SUBSTRING ( t.thetime FROM 13 FOR 2 )||'.00'
) AS TIMESTAMP)

Then I tried to include it in int using this technique

CAST(cast(
(SUBSTRING ( t.thetime FROM 5 FOR 2 )||'/'||SUBSTRING ( t.thetime FROM 7 FOR 2 )||'/'||SUBSTRING ( t.thetime FROM 1 FOR 4 )||' '|| SUBSTRING ( t.thetime FROM 9 FOR 2 )||':'||SUBSTRING ( t.thetime FROM 11 FOR 2 )||':'||SUBSTRING ( t.thetime FROM 13 FOR 2 )||'.00'
) AS TIMESTAMP)
-cast('01/01/1970 00:00:00' as timestamp) as BIGINT) as TIMESTAMP_INT

I get an integer, but it looks like the return value is the number of days or something like that.

eg. 01/08/2015, 16: 33: 01.114 becomes 16444

Any suggestions why this is happening or is there another way to do this?

I am using Firebird version 2.5

Thanks in advance

PS:

SELECT 
CAST(cast(
    (SUBSTRING ( '20140108154821' FROM 5 FOR 2 )||'/'||SUBSTRING ( '20140108154821' FROM 7 FOR 2 )||'/'||SUBSTRING ( '20140108154821' FROM 1 FOR 4 )||' '
    ||
    SUBSTRING ( '20140108154821' FROM 9 FOR 2 )||':'||SUBSTRING ( '20140108154821' FROM 11 FOR 2 )||':'||SUBSTRING ( '20140108154821' FROM 13 FOR 2 )||'.00'
    ) AS TIMESTAMP)
    -cast('01/01/1970 00:00:00' as timestamp) as BIGINT) 
    from sometable

;

Answer 1

- DATEDIFF:

SELECT DATEDIFF(second, TIMESTAMP'1970-01-01 00:00', CURRENT_TIMESTAMP) 
FROM RDB$DATABASE

, UTC, (, CET (UTC + 1) TIMESTAMP'1970-01-01 01:00').

Answer 2

, , - . , , " " , ,

SELECT floor((yourTIMESTAMP - cast('1970-01-01' as TIMESTAMP)) * 86400)
FROM rdb$database

yourTIMESTAMP , , 86400 - .