I have the following WHERE clause in my query:
START_DATE=SYSDATE-:P1_NUM_OF_DAYS
how can I change my where clause to return ALL the records when P1_NUM_OF_DAYS is NULL?
I presume you should rather use trunc(sysdate) than pure sysdate (which contains time component).
Anyway, here you go:
where start_date = case when :P1_NUM_OF_DAYS is null then start_date
else trunc(sysdate) - :P1_NUM_OF_DAYS
end
Related
i have a select(water readings, previous water reading, other columns) , a "where clause" that is based on date water reading date. however for previous water reading it must not consider the where clause. I want to get previous meter reading regardless where clause date range.
looked at union problem is that i have to use the same clause,
SELECT
WATERREADINGS.name,
WATERREADINGS.date,
LAG( WATERREADINGS.meter_reading,1,NULL) OVER(
PARTITION BY WATERREADINGS.meter_id,WATERREADINGS.register_id
ORDER BY WATERREADINGS.meter_id DESC,WATERREADINGS.register_id
DESC,WATERREADINGS.readingdate ASC,WATERREADINGS.created ASC
) AS prev_water_reading,
FROM WATERREADINGS
WHERE waterreadings.waterreadingdate BETWEEN '24-JUN-19' AND
'24-AUG-19' and isactive = 'Y'
The prev_water_reading value must not be restricted by the date BETWEEN '24-JUN-19' AND '24-AUG-19' predicate but the rest of the sql should be.
You can do this by first finding the previous meter readings for all rows and then filtering those results on the date, e.g.:
WITH meter_readings AS (SELECT waterreadings.name,
waterreadings.date dt,
lag(waterreadings.meter_reading, 1, NULL) OVER (PARTITION BY waterreadings.meter_id, waterreadings.register_id
ORDER BY waterreadings.readingdate ASC, waterreadings.created ASC)
AS prev_water_reading,
FROM waterreadings
WHERE isactive = 'Y')
-- the meter_readings subquery above gets all rows and finds their previous meter reading.
-- the main query below then applies the date restriction to the rows from the meter_readings subquery.
SELECT name,
date,
prev_water_reading,
FROM meter_readings
WHERE dt BETWEEN to_date('24/06/2019', 'dd/mm/yyyy') AND to_date('24/08/2019', 'dd/mm/yyyy');
Perform the LAG in an inner query that is not filtered by dates and then filter by the dates in the outer query:
SELECT name,
"date",
prev_water_reading
FROM (
SELECT name,
"date",
LAG( meter_reading,1,NULL) OVER(
PARTITION BY meter_id, register_id
ORDER BY meter_id DESC, register_id DESC, readingdate ASC, created ASC
) AS prev_water_reading,
waterreadingdate --
FROM WATERREADINGS
WHERE isactive = 'Y'
)
WHERE waterreadingdate BETWEEN DATE '2019-06-24' AND DATE '2019-08-24'
You should also not use strings for dates (that require an implicit cast using the NLS_DATE_FORMAT session parameter, which can be changed by any user in their own session) and use date literals DATE '2019-06-24' or an explicit cast TO_DATE( '24-JUN-19', 'DD-MON-RR' ).
You also do not need to reference the table name for every column when there is only a single table as this clutters up your code and makes it difficult to read and DATE is a keyword so you either need to wrap it in double quotes to use it as a column name (which makes the column name case sensitive) or should use a different name for your column.
I've added a subquery with previous result without filter and then joined it with the main table with filters:
SELECT
WATERREADINGS.name,
WATERREADINGS.date,
w_lag.prev_water_reading
FROM
WATERREADINGS,
(SELECT name, date, LAG( WATERREADINGS.meter_reading,1,NULL) OVER(
PARTITION BY WATERREADINGS.meter_id,WATERREADINGS.register_id
ORDER BY WATERREADINGS.meter_id DESC,WATERREADINGS.register_id
DESC,WATERREADINGS.readingdate ASC,WATERREADINGS.created ASC
) AS prev_water_reading
FROM WATERREADINGS) w_lag
WHERE waterreadings.waterreadingsdate BETWEEN '24-JUN-19' AND '24-AUG-19' and isactive = 'Y'
and WATERREADINGS.name = w_lag.name
and WATERREADINGS.date = w_lag.date
i have a problem with a date parameter query using 'between' operator in oracle view, when i do this query :
SELECT *
FROM MY_VIEW
WHERE STATUS = 'Active'
AND CHECKER_DATE BETWEEN to_date(sysdate - 1, 'DD-MON-YY') AND to_date(sysdate, 'DD-MON-YY');
it does not give me the records (actualy i have any record on that date).
I try using 'in' operator, but still not give me the records.
Please throw some information for this.
*checker_date defined as date
Your first error is to call to_date() on a value that is already a DATE. to_date() expects a VARCHAR value, so sysdate will be first converted to VARCHAR and will then immediately be converted back to a DATE value which it was to begin with.
You probably want
AND CHECKER_DATE BETWEEN trunc(sysdate) - 1 AND trunc(sysdate)
Most probably this will still not give you want you want as that would not include rows from "today". trunc(sysdate) means "today at midnight" and any row that was created today after midnight will not be included. With date/time values (and Oracle's DATE type does contain a time, despite the name) it's better to not use BETWEEN, but explicit range operators instead:
AND CHECKER_DATE >= trunc(sysdate) - 1
AND CHECKER_DATE < trunc(sysdate) + 1
trunc(sysdate) + 1 is tomorrow at midnight, so any value that is (strictly) smaller than that is "today".
All the above assumes that CHECKER_DATE is defined as DATE or TIMESTAMP
You can try:
SELECT *
FROM MY_VIEW
WHERE STATUS = 'Active'
AND CHECKER_DATE BETWEEN trunc(sysdate - 1) AND trunc(sysdate);
Oracle advises against using to_date for date. Also trunc is here because Trunc removes the time component.
may be records are not 'Active' or 'Active' a not-existing value in one of the reference tables if any and trunc(sysdate -1) and trunc(sysdate) would help
Is there any method to reduce the time taken to get the result from below query?
Please help. Thanks in advance!
select status, count(distinct id)
from emp
where id >=
( select min(id)
from emp
where id >= (select max(id-200000) from emp)
and trunc(join_date) >= '01-Mar-2018')
group by status;
Use analytic functions - this will perform only a single table scan (whereas your query has three table/index scans):
SELECT status,
COUNT( DISTINCT id )
FROM (
SELECT status,
id,
MIN( CASE WHEN join_date >= DATE '2018-03-01' THEN id END ) OVER () AS min_id
FROM (
SELECT status,
id,
join_date,
MAX( id ) OVER () AS max_id
FROM emp
)
WHERE id >= max_id - 20000
)
WHERE id >= min_id
GROUP BY status;
Also, you can use a date literal (rather than relying on implicit conversion of a string to a date using the NLS_DATE_FORMAT session parameter) and you do not need to use the TRUNC() function (since that may prevent Oracle using an index on the join_date column and would instead require a function-based index).
It is important to know if id is a primary key (as columns with that name usually are) or not. If it is not, you definitely need an index on id for it to perform (and I would also wonder what the purpose of the column was). If id is the primary key, you don't need to the distinct as the values will be unique anyway.
The select min(id) sub-select is redundant as you already found max(id - 200000) so you don't need to know the first min(id) greater than that. You can just use >= by itself (with the condition on the date added). By the way, I would write max(id) - 200000 instead; on some databases, it might work better.
The date comparison may be problematic. You should try an index on join_date if you haven't got one already, but the trunc might stop that from being used, so it would be best to remove that and make the other side of the compare use a TO_TIMESTAMP or TO_DATE to generate a corresponding literal as appropriate, setting the time to midnight.
But there can be problems with comparing timestamps due to timezones, etc. I'd need to know more about your setup to know whether that is likely to be a problem.
I am writing an SQL query where the query should first search the first value, and only if this value is missing the query should search for the second value.
I have two tables. One of these tables contains the modification date (this is not always filled and can be null) and a creation date which is always filled.
Now what I want is that the query first looks in the table with the modification date and only if it is null looks at the table with the creation date.
Example of the query:
Select *
from all_articles
where to_char(modification_date, 'YYYYMMDD') = to_char(sysdate, 'YYYYMMDD')-1
-- if this is an empty record then
to_char(creation_date, 'YYYYMMDD') = to_char(sysdate, 'YYYYMMDD')-1
Can anyone help me with this query?
Almost all the major RDBMS' available have in built functions to handle such a situation.
The Oracle DB has NVL function which works as follows:
NVL(Modified_dt, Create_dt);
The above will return Modified_dt column data by default. However, if that isn't available, it will return Create_dt.
See here for details:
http://www.w3schools.com/sql/sql_isnull.asp
A database column (VARCHAR2 datatype) stores the date/time as 13 digit (milliseconds
) unixtimestamp format. Now when I want to compare the column with a oracle date (in question), The error thrown as 'invalid number'
I tried both ways,
converting the 13digit number to Date and compare with the date in question like below. The expressions seems valid as they are printed in select query, but if i include in the where part, it throws 'invalid number'
Here 'value' is 13th digit unixtimestamp column of VARCHAR2 datatype.
select
TO_DATE('1970-01-01', 'YYYY-MM-DD') + value/86400000,
TO_DATE('2014-04-21', 'YYYY-MM-DD')
from dummytable
-- where and TO_DATE('1970-01-01', 'YYYY-MM-DD') + value/86400000 > TO_DATE('2014-04-21', 'YYYY-MM-DD')
converting the date in question to 13digit unixtimestamp and comparing with the database column.The expressions seems valid as they are printed in select query, but if i include in the where part, it throws 'invalid number'
.
select
value,
(to_date('2013-04-21', 'YYYY-MM-DD') - to_date('1970-01-01', 'YYYY-MM-DD')) * (1000*24*60*60)
from dummytable
-- where value > ((to_date('2013-04-21', 'YYYY-MM-DD') - to_date('1970-01-01', 'YYYY-MM-DD')) * (1000*24*60*60))
any pointers? Thanks in advance.
[EDIT- 1 day later] I see the problem now. There are some data (other rows) for the 'value' column that are non-numeric. But I have another column say field, where always field='date' return value as 13 digit timestamp. Now I think when 'where' condition executes, although the field='date' is in the condition, it is still validating the other values for 'value' which are non-numeric. Is there a way to avoid this ?
Your code works just fine. The problem is in your data. Some of your values is not a number.
create table test
(value varchar2(13));
insert into test(value) values('2154534689000');
--insert into test(value) values('2 54534689000');
select TO_DATE('1970-01-01', 'YYYY-MM-DD') + value/86400000
from test
where TO_DATE('1970-01-01', 'YYYY-MM-DD') + value/86400000 > TO_DATE('2014-04-21', 'YYYY-MM-DD');
This code works fine. But if you uncommented the second insert, you would get exactly the same invalid number error as you get.
UPD. Allan gave you a nice hint, but i feel that it can be good to explain you a bit about views. The fact that you select from a view CAN make a difference. A view is not stored somewhere physically, when you select from it, it is just "added to your query". And then Oracle Query Optimizer starts working. Among other things, it can change the order in which your where predicates are evaluated.
For example, your the view query can have a line where value is not null and it would normally show only 'good' values. But if your query has a predicate where to_date(value,'ddmmyyyy') > sysdate, Oracle can decide to evaluate your predicate earlier, because Oracle predicts that it would "cut off" more rows, thus making the whole query faster and less momery consuming. Of course, execution will crash because of an attempt to convert a null string to date.
I believe, that Allan in his answer that he gave a link to, gave a great way to solve this problem: "wrapping" your query in a subquery that Oracle can't "unwrap":
select value
from
(select value
from my_view
where rownum > 0)
where to_date(value,'ddmmyyyy') > sysdate
Hope that helps.