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!
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;
As an alternative to adding fractional days via expressions such as "5 / 24" you might want to use an INTERVAL constant. For example:
SELECT count(*)
FROM my_table
WHERE my_date BETWEEN (TRUNC(SYSDATE) + INTERVAL '5' HOUR)
AND (TRUNC(SYSDATE) + INTERVAL '1' DAY +
INTERVAL '5' HOUR - INTERVAL '1' SECOND) AND
my_code='33'
GROUP BY my_code
I like to use INTERVAL constants because it's quite clear what these constants represent. With the fractional-day constants I sometimes get confused ('course, I sometimes get confused, regardless... :-)
Share and enjoy.
If I understand correctly, something like
select count(*)
from my_table
where trunc(my_date) = trunc(sysdate)
and my_code = '33'
group by my_code;
or
select count(*)
from my_table
where my_date
between sysdate and sysdate + 5/24
and my_code = '33'
group by my_code;
HTH.
Alessandro
Related
I’m experiencing some issues while using the Current_Date function in a simple query and I haven’t been able to figure out why. I’m working in an Oracle 12c environment using Oracle SQL Developer 3.2.
My original query looks something like this:
select * from Inventory where Placement_End_Dt >= Current_date
The above works fine except it doesn’t pick up records where Placement_End_Dt is today (14th May 18)
I attempted to simplify the query as follows, but this also returns nothing
select * from Inventory where Placement_End_Dt = Current_date
However when I apply date formatting as follows, it works:
select * from Inventory where to_char(Placement_End_Dt, 'DD-MM-YYYY') = to_char(Current_date, 'DD-MM-YYYY')
Then I try and expand on this to revert to my original query to select all records with an end date from today onwards:
select * from Inventory where to_char(Placement_End_Dt, 'DD-MM-YYYY') => to_char(Current_date, 'DD-MM-YYYY')
This fails spectacularly because it selects records with a Placement_End_Dt past, present and future!
The Placement_End_Dt columns is defined as an Oracle DATE data type
Would appreciate some input on how I can get this query to work.
When using to_char you are comparing strings.
to_char(date '2000-01-20', 'DD-MM-YYYY') > to_char(date '2018-05-14', 'DD-MM-YYYY')
because '20-01-2000' is greater than '14-05-2018', because of the first letters in the strings: '2' > '1'.
And CURRENT_DATE is hardly ever used, because it uses your computer's time, rather than the database time, so you can easily be some hours off. Use SYSDATE instead.
I would suggest using this query
select * from Inventory where trunc(Placement_End_Dt) = trunc(sysdate);
Oracle Date columns also store a timestamp by default, so unless the records were the same down to the second, they won't match. When you use trunc() on a date column, it truncates the timestamp and leaves just the date.
Try this, it will return the rows for present days and future days.
select * from Inventory where trunc(Placement_End_Dt) >= trunc(sysdate);
I would like to filter out the data using a sub query in the interval function
Following is the query i use
SEL * FROM my_table WHERE MY_DATE < CURRENT_DATE- INTERVAL '30' MONTH;
The above query works, However i want to parameterize the period '30' using a sub query. Please suggest how to achieve this.
Thanks in Advance
Don't use interval calculations with year/month as it will fail, e.g. DATE '2016-12-31' + INTERVAL '30' MONTH results in 2019-06-31 (according to Standard SQL) which obviously doesn't exist.
SELECT *
FROM my_table
WHERE MY_DATE < ADD_MONTHS(CURRENT_DATE, (SELECT -col FROM tab));
If col is actually an INTERVAL you need to cast it to an INT.
I have a table where I have multiple integer columns: year, month and day. Unfortunately, while the three should have been grouped into one DATE column from the beginning, I am now stuck and now need to view it as such. Is there a function that can do something along the lines of:
SELECT makedate(year, month, day), othercolumn FROM tablename;
or
SELECT maketimestamp(year, month, day, 0, 0), othercolumn FROM tablename;
You can
SELECT format('%s-%s-%s', "year", "month", "day")::date
FROM ...
or use date maths:
SELECT DATE '0001-01-01'
+ ("year"-1) * INTERVAL '1' YEAR
+ ("month"-1) * INTERVAL '1' MONTH
+ ("day"-1) * INTERVAL '1' DAY
FROM ...
Frankly, it's surprising that PostgreSQL doesn't offer a date-constructor like you describe. It's something I should think about writing a patch for.
In fact, a quick look at the sources shows that there's an int date2j(int y, int m, int d) function at the C level already, in src/backend/utils/adt/datetime.c. It just needs to be exposed at the SQL level with a wrapper to convert to a Datum.
OK, now here's a simple makedate extension that adds a single function implemented in C, named makedate. A pure-SQL version is also provided if you don't want to compile and install an extension. I'll submit the C function for the 9.4 commitfest; meanwhile that extension can be installed to provide a fast and simple date constructor:
regress=# SELECT makedate(2012,01,01);
makedate
------------
2012-01-01
(1 row)
PostgreSQL 9.4+
In PostgreSQL 9.4, a function was added to do just this
make_date(year int, month int, day int)
There may be a more elegant method, but this will give you a date.
select to_date(to_char(year * 10000 + month * 100 + day,'00000000'), 'yyyymmdd')
from tablename;
Try something like:
SELECT year * interval '1 year' +
month * interval '1 month' +
day * interval '1 day'
FROM tablename;
I have a table with date column in it. I need to fetch the records from it based on
the given date.
Currently when i used the query:
select * from workingemployee_data where created_date like '20-Jan-2012'
I am getting those records which have created_date on 20-Jan-2012
But i want to get the records those were created 10 days earlier to a given
date (i.e) 20-Jan-2012.
Please suggest me on this.
This gives all records between today and 10 days ago:
SELECT *
FROM workingemployee
WHERE created_date BETWEEN sysdate - INTERVAL '10' DAY
AND sysdate
This gives all records entered exactly 10 days ago:
SELECT *
FROM workingemployee
WHERE created_date = sysdate - INTERVAL '10' DAY
Replace sysdate with exact date if you want.
Why do you use like and not = ?
Assuming that created_date is of type DATE, it's bad practice to rely on implicit conversion according to NLS_DATE_FORMAT (this is what happens when you compare a date and a string)
dd-mon-yyyy isn't a good format for querying since it deffers according to NLS_LANGUAGE better use mm for months numbers
So, either use #mvp's answer or do something like this:
SELECT *
FROM workingemployee
WHERE trunc(created_date) = to_date('20-01-2013', 'dd-mm-yyyy') - 10
SELECT *
FROM workingemployee
WHERE created_date > sysdate - INTERVAL '10' DAY;
I need to get the difference of 2 date fields, if the greater date is null then I'll use SYSDATE instead. Having this requirement, I created a function to solve this issues (note: this code follows the standard of the organization, not my personal taste)
CREATE FUNCTION F_GET_DIFFERENCE (P_WORKFLOWID NUMBER)
RETURN NUMBER --result in minutes
IS
TIME NUMBER;
BEGIN
TIME := 0
SELECT
F_WORKTIME_DIFF(NVL(X.ENDDATE, SYSDATE), X.STARTDATE)
INTO
TIME
FROM
TABLEX X
WHERE
X.WORKFLOWID = P_WORKFLOWID;
RETURN TIME;
EXCEPTION
WHEN OTHERS THEN
RETURN 0;
END;
The F_WORKTIME_DIFF function already exists and calculates the worktime of the day (assumming nobody works at 12 a.m. and things like that). The problem is when calling this function, the result contains an additional amount of time. That's very strange, because when executing the query in the function, it returns the expected output.
Example (important: date format in Peru is DD/MM/YYYY HH24:MI:SS)
TABLEX
WORKFLOWID STARTDATE ENDDATE
1 '01/12/2012 10:00:00' null
Assumming that the server day is the same day (01/12/2012) but greater time (10:01:00), we execute the function:
SELECT F_GET_DIFFERENCE(1)
FROM DUAL;
The result is: 14.
Now, executing the query in the function and having the server time at 10:02:00, the result is 2 (exact output).
I even tried executing this
SELECT
F_WORKTIME_DIFF(NVL(X.ENDDATE, SYSDATE), X.STARTDATE) SELECT_WAY,
F_GET_DIFFERENCE(1) FUNCTION_WAY
FROM
TABLEX X
WHERE
X.WORKFLOWID = 1
And the result is (having the server time at 10:10:00)
SELECT_WAY FUNCTION_WAY
10 24
Is maybe any consideration that I must take into account when working with Oracle dates in inner functions or anything that could explain this odd behavior?
It is difficult to tell anything without seeing the function F_WORKTIME_DIFF.
Whatever is the datatype returned from F_WORKTIME_DIFF, it is casted to number when assigned to the variable time. This may be a clue.
This may not be exactly what are you looking for but the first example gives you hours diff between two dates:
Select EXTRACT(HOUR FROM (SYSDATE - trunc(SYSDATE )) DAY TO SECOND ) From dual
/
Select
EXTRACT(hour From Cast(SYSDATE as timestamp)) hh,
EXTRACT(minute From Cast(SYSDATE as timestamp)) mi,
EXTRACT(second From Cast(SYSDATE as timestamp)) ss
From dual
/