oracle SQL 如何从日期中删除时间

Question

I have a column named StartDate containing a date in this format: 03-03-2012 15:22

What I need is to convert it to date. It should be looking like this: DD/MM/YYYY

What I have tried without success is:

select 
p1.PA_VALUE as StartDate,
p2.PA_VALUE as EndDate
from WP_Work p 
LEFT JOIN PARAMETER p1 on p1.WP_ID=p.WP_ID AND p1.NAME = 'StartDate'
LEFT JOIN PARAMETER p2 on p2.WP_ID=p.WP_ID AND p2.NAME = 'Date_To'
WHERE p.TYPE = 'EventManagement2'
AND TO_DATE(p1.PA_VALUE, 'DD/MM/YYYY') >= TO_DATE('25/10/2012', 'DD/MM/YYYY')
AND TO_DATE(p2.PA_VALUE, 'DD/MM/YYYY') <= TO_DATE('26/10/2012', 'DD/MM/YYYY')

Is there a way to do this?

EDIT1: the PA_VALUE column is: VARCHAR2

Answer 1

You can use TRUNC on DateTime to remove Time part of the DateTime. So your where clause can be:

AND TRUNC(p1.PA_VALUE) >= TO_DATE('25/10/2012', 'DD/MM/YYYY')

The TRUNCATE (datetime) function returns date with the time portion of the day truncated to the unit specified by the format model.

Answer 2

When you convert your string to a date you need to match the date mask to the format in the string. This includes a time element, which you need to remove with truncation:

select 
    p1.PA_VALUE as StartDate,
    p2.PA_VALUE as EndDate
from WP_Work p 
LEFT JOIN PARAMETER p1 on p1.WP_ID=p.WP_ID AND p1.NAME = 'StartDate'
LEFT JOIN PARAMETER p2 on p2.WP_ID=p.WP_ID AND p2.NAME = 'Date_To'
WHERE p.TYPE = 'EventManagement2'
AND trunc(TO_DATE(p1.PA_VALUE, 'DD-MM-YYYY HH24:MI')) >= TO_DATE('25/10/2012', 'DD/MM/YYYY')
AND trunc(TO_DATE(p2.PA_VALUE, 'DD-MM-YYYY HH24:MI')) <= TO_DATE('26/10/2012', 'DD/MM/YYYY')

Answer 3

We can use TRUNC function in Oracle DB. Here is an example.

SELECT TRUNC(TO_DATE('01 Jan 2018 08:00:00','DD-MON-YYYY HH24:MI:SS')) FROM DUAL

Output: 1/1/2018

Answer 4

Try

SELECT to_char(p1.PA_VALUE,'DD/MM/YYYY') as StartDate,
       to_char(p2.PA_VALUE,'DD/MM/YYYY') as EndDate
   ...

Answer 5

If your column with DATE datatype has value like below : -

value in column : 10-NOV-2005 06:31:00

Then, You can Use TRUNC function in select query to convert your date-time value to only date like - DD/MM/YYYY or DD-MON-YYYY

select TRUNC(column_1) from table1;

result : 10-NOV-2005

You will see above result - Provided that NLS_DATE_FORMAT is set as like below :-

Alter session NLS_DATE_FORMAT = 'DD-MON-YYYY HH24:MI:SS';