Question

I have the following in a SQL Server query which I have to convert to Oracle sp

DATEADD(dd, 0, DATEDIFF(dd, 0, DATEADD(ss, -L_LAST_TIME, TR.TR_DATETIME))) AS TRDATE,

Essentially you subtract L_LAST_TIME seconds from TR_DATETIME and then truncate the time part and keep only the date part.

Answer 1

You can divide intervals:

select trunc(TR.TR_DATETIME - interval L_LAST_TIME SECOND) AS TRDATE  

or

select trunc(TR.TR_DATETIME - NUMTODSINTERVAL(L_LAST_TIME, 'SECOND')) AS TRDATE