I need to compare date with date of current day, using SYSDATE, something like this:
SELECT * FROM my_table
WHERE date_column BETWEEN TO_DATE(SYSDATE -3,'dd.mm.yyyy') AND TO_DATE(SYSDATE,'dd.mm.yyyy');
However, this produces no result....My question :
Based on accepted answer here we should NEVER EVER compare strings with date. But in other side, a SYSDATE is allready a Date data type, and we should not compare It to a date - see here.
If I replace TO_DATE with TO_CHAR in upper SQL things go working again. But TO_CHAR function converts into String, so Oracle (I pressume) needs to convert this string again to date so you force Oracle to do an implicit data type conversion.
So, what should be a correct comparison with date and SYSDATE, in order to avoid Oracle working a bit slowly ?
You should not need to call either TO_DATE or TO_CHAR:
SELECT *
FROM my_table
WHERE date_column >= TRUNC(SYSDATE - 3) AND date_column < TRUNC(SYSDATE + 1);
Assuming date_column is a date type, you should be able to directly compare it against SYSDATE, or SYSDATE offset by some number of days.
Related
I have this query in oracle:
DELETE FROM my_table
WHERE to_date(last_update, 'DD/MM/YYYY') < to_date('01/01/2000', 'DD/MM/YYYY');
when I run this, I get this error:
ORA-01841: (full) year must be between -4713 and +9999 and must not be 0
there is not any 0 value in the table.
any one knows what is the problem?
I am assuming that you have stored your dates as a string with the DD/MM/YYYY format; it would be better if you stored them all as a DATE data type and then you would not have to do this conversion (and you would be using the most appropriate data type for the data).
From Oracle 12, you can use:
SELECT *
FROM my_table
WHERE TO_DATE( last_update, 'DD/MM/YYYY' DEFAULT NULL ON CONVERSION ERROR ) IS NULL;
To identify the rows that are raising that exception.
If you are already storing them as a DATE data type then don't use TO_DATE on a value that is already a DATE as TO_DATE expects a string so Oracle will implicitly cast your DATE to a string and then try to convert it back and your query is effectively:
DELETE FROM my_table
WHERE TO_DATE(
TO_CHAR(
last_update,
( SELECT value FROM NLS_SESSION_SETTINGS WHERE PARAMETER = 'NLS_DATE_FORMAT' )
),
'DD/MM/YYYY'
) < to_date('01/01/2000', 'DD/MM/YYYY');
And if the NLS_DATE_FORMAT and your format model do not match then you will get errors (or, worse, the query will succeed and your data will be inconsistent as it may have swapped days and months or months and years).
Instead, just use:
DELETE FROM my_table
WHERE last_update < DATE '2000-01-01';
If the datatype of last_update is date, don't use the to_date function:
DELETE FROM my_table
WHERE last_update < to_date('01/01/2000', 'DD/MM/YYYY');
I'm just trying to fetch Hour of my table from created date in Oracle 12c Database but it is showing error INVALID EXTRACT FIELD FOR EXTRACT FIELD. kindly guide me to fetch hour of my date my code is here...
SELECT
EXTRACT( HOUR FROM (TO_CHAR(CREATED_DATE,'RRRR-MM-DD HH:MI:SS')) ) HOUR
FROM
INVOICE_V;
my Date is stored as 6/1/2020 4:04:50 PM in this format and Extract function is not accept this function.
Do not store dates as strings.
But, since you have, convert it from a string to a date using TO_DATE:
SELECT EXTRACT( HOUR FROM TO_TIMESTAMP(CREATED_DATE,'DD/MM/YYYY HH12:MI:SS AM') ) AS HOUR
FROM INVOICE_V;
If, however, you meant that its just displaying in that format (and is actually a DATE data type) then CAST the date to a timestamp:
SELECT EXTRACT( HOUR FROM CAST( CREATED_DATE AS TIMESTAMP) ) AS HOUR
FROM INVOICE_V;
An hour can not be used in the EXTRACT function.
The only way to extract hour is to use TO_CHAR or subtract it from TRUNC date as follows:
TO_CHAR(created_date,'HH24') -- OR 'HH' as per your requirement
-- OR
FLOOR(24*(created_date- TRUNC(created_date)))
Please note that Oracle does not store dates in any format. It has its own binary representation. What you see while selecting from the table is based on the NLS_DATE_FORMAT parameter.
You can set it according to your requirement.
ALTER SESSION SET NLS_dATE_FORMAT = 'YYYY-MM-DD HH24:MI:SS'; -- like this
If you have a date column (or the-like), then:
select extract(hour from cast(created_date as timestamp)) as hr
from invoice_v
Alternatively:
select to_char(created_date, 'hh24') as hr
from invoice_v
The first expression returns an integer number, while the second produces a string.
Note that hour is a language keyword, hence not a good choice for an identifier (here, you used it as a column alias). I changed that.
Why does below query work successfully?
select to_char(sysdate,'MM-YYYY') from dual;
But the following queries give an invalid number error:
select to_char('28-JUL-17','MM-YYYY') from dual;
select to_char('7/28/2017','MM-YYYY') from dual;
Though, below query gives you the same date format.
select sysdate from dual; -- 7/28/2017 11:29:01 AM
TO_CHAR function accepts only date or number. Maybe you can try this
select to_char(to_date('28-JUL-17', 'DD-MON-YY'),'MM-YYYY') from dual;
As a side note, if you're planning to convert a bunch of dates to strings so you can look for all records in a certain month of a certain year, be aware that the TRUNC function can be used to reduce the precision of a date (e.g. to "month and year"). The following query pulls all records created this month, from the table. It should be faster than converting dates to char and doing string comparison..
SELECT * FROM table WHERE trunc(create_date, 'MON') = trunc(sysdate, 'MON')
Because function TO_CHAR() accepts date or timestamp values. However, neither '28-JUL-17' nor '7/28/2017' are dates or timestamps - they are STRINGS.
Oracle gently tries to convert these stings into DATE values. This implicit conversion may work or may fail, it depends on your current session NLS_DATE_FORMAT, resp. NLS_TIMESTAMP_FORMAT settings.
As given already in other answers you have to convert the string explicitly:
TO_DATE('28-JUL-17', 'DD-MON-RR')
TO_DATE('7/28/2017', 'MM/DD/YYYY')
to_char() isn't expecting you to start with a char value. If you really want that to work, you'll need to wrap it around a to_date() function.
to_char(
to_date(
'28-JUL-17'
, 'DD-Mon-YY'
)
,'MM-YYYY'
)
You are using an incorrect mask, for more information read here.
The correct one should be:
select to_char(to_date('28-JUL-17','DD-MON-YY'), 'MON-YY') from dual;
You can also extract the month using EXTRACT:
select EXTRACT (MONTH FROM to_date('28-JUL-17','DD-MON-YY')) from dual;
Cheers
For eg I have a student table with a DOJ(date of joining) column with its type set as DATE now in that I have stored records in dd-mon-yy format.
I have an IN param at runtime with date passed as string and its in dd/mm/yyyy format. How do I compare and fetch results on date?
I want to fetch count of records of students who have DOJ of 25-AUG-92 per my database table student, but I am getting date as varchar in dd/mm/yyyy format in an IN param, kindly please guide.
I have tried multiple options such as trunc, to_date, to_char but, unfortunately nothing seems to work.
I have a student table with a DOJ(date of joining) column with its type set as DATE now in that I have stored records in dd-mon-yy format.
Not quite, the DATE data-type does not have a format; it is stored internally in tables as 7-bytes (year is 2 bytes and month, day, hour, minute and second are 1-byte each). The user interface you are using (i.e. SQL/PLUS, SQL Developer, Toad, etc.) will handle the formatting of a DATE from its binary format to a human readable format. In SQL/Plus (or SQL Developer) this format is based on the NLS_DATE_FORMAT session parameter.
If the DATE is input using only the day, month and year then the time component is (probably) going to be set to 00:00:00 (midnight).
I have an IN param at runtime with date passed as string or say varchar and its in dd/mm/yyyy format. How do I compare and fetch results on date.?
Assuming the time component for you DOJ column is always midnight then:
SELECT COUNT(*)
FROM students
WHERE doj = TO_DATE( your_param, 'dd/mm/yyyy' )
If it isn't always midnight then:
SELECT COUNT(*)
FROM students
WHERE TRUNC( doj ) = TO_DATE( your_param, 'dd/mm/yyyy' )
or:
SELECT COUNT(*)
FROM students
WHERE doj >= TO_DATE( your_param, 'dd/mm/yyyy' )
AND doj < TO_DATE( your_param, 'dd/mm/yyyy' ) + INTERVAL '1' DAY
The below should do what you've described. If not, provide more information on how "nothing seems to work".
-- Get the count of students with DOJ = 25-AUG-1992
SELECT COUNT(1)
FROM STUDENT
WHERE TRUNC(DOJ) = TO_DATE('25/AUG/1992','dd/mon/yyyy');
The above was pulled from this answer. You may want to look at the answer, because if performance is critical to you, there is a different way to write this query which doesn't use trunc, which will allow Oracle to use index on DOJ, if one is present.
Though I am bit late in posting this but I have been able to resolve this.
What I did was I converted both the dates to_char in similar formats and it worked here is my query condition that worked..
TO_CHAR(TO_DATE(C.DOB, 'DD-MON-YY'),'DD-MON-YY')=TO_CHAR(TO_DATE(P_Dob,'DD/MM/YYYY'),'DD-MON-YY'))
Thanks for the support all. :)
I have a date type column in a table, where I store date along with time.
I want to query it by WHERE clause
I did it this way:
select *
from conference_hall_book
where to_date(end_time,'dd/mon/yyyy hh24:mi:ss') <= to_date('26/oct/2013 15:00:00','dd/mon/yyyy hh24:mi:ss')
But the result has 27/10/2013 8:00:00 AM also in end_time column.
Can any one help me finding the mistake?
The problem occurs because of
to_date(end_time,'dd/mon/yyyy hh24:mi:ss')
This is a wrong usage of the to_date function. To_date converts a string to a date.
When Oracle sees this expression, it will automatically convert the end_time value to a string, using the configured date format of your database/session. This format typically doesn't include the time part, so a date with the value of "27/10/2013 8:00:00 AM" will be converted to the string "27/10/2013" (if your database date format is dd/mm/yyyy).
Your to_date expression will then convert the string value "27/10/2013" back to a date. The resulting date value will be "27/10/2013 00:00:00", so you will have lost the time portion of your original date.
The simple and correct solution is to drop the to_date(end_time) expression and just use end_time. This will also ensure that if you have index on end_time, the query will be able to use that index.
select *
from conference_hall_book
where end_time <= to_date('26/oct/2013 15:00:00','dd/mon/yyyy hh24:mi:ss')