Question

I am trying to optimize a simple SQL query and was wondering if anyone has any suggestions. I am developing using Oracle SQL Developer (which I don’t like) on an Oracle 11g database. The query I am using is:

SELECT count(*) 
FROM my_table 
WHERE my_date
BETWEEN TO_DATE('2012-5-09T05.00.00','YYYY-MM-DD"T"HH24:MI:SS') 
AND TO_DATE('2012-5-10T04.59.59','YYYY-MM-DD"T"HH24:MI:SS') 
AND my_code='33' 
GROUP BY my_code;

Also, I want to be able to use this query dynamically by changing the part of the date to be whatever the current date is, but I want to be able to specify the hour. So I want to be comparing something like:

getdate() + 'T05.00.00'

I have no idea how to do this and the getdate() function doesn’t seem to work in SQL Developer/I don’t know how to use it correctly.

So what I’m looking for is optimization suggestions and pointers on how to just dynamically change the day-month-year part of the date I want to constrain my results to. Thanks!

Answer 1

To get current date, you can use SYSDATE. To add x number of hours to it, you can add x/24. So something like this:

Example: Get current date + 5 hours

 SELECT SYSDATE + 5/24 FROM dual

So in your example:

SELECT count(*) 
FROM my_table 
WHERE my_date
BETWEEN sysdate
AND sysdate + 5/24 -- if you want 5 hours ahead, for example
AND my_code='33' 
GROUP BY my_code;

If you want to be able to change the number of hours, you could make this code into a function, and pass in the hours and code as variables.

Something like this:

CREATE FUNCTION myfunc
(
   p_num_hours INT
 , p_my_code VARCHAR
) RETURN INT
AS
  l_ret INT;
BEGIN
   SELECT count(*) 
   INTO l_ret
   FROM my_table 
   WHERE my_date
   BETWEEN sysdate
   AND sysdate + p_num_hours/24
   AND my_code=p_my_code 

   RETURN l_ret;
END;