How to convert a date to a string - sql

Question

I want yo get only the 'date hours:minutes:seconds' from the Date column
Date
10/11/22 12:14:01,807000000
11/12/22 13:15:46,650000000
29/12/22 14:30:46,501000000
and I want to get a string column with date hours:minutes:seconds
Date_string
10/11/22 12:14:01
11/12/22 13:15:46
29/12/22 14:30:46
I tried this code but it doesn't work:
select*, TO_CHAR(extract(hour from (Date)))||':'||TO_CHAR(extract(minute from (Date)))||':'||TO_CHAR(extract(second from (Date))) as Date_string
from table;

Answer 1

If this is a date column, you could use to_char directly:
SELECT m.*, TO_CHAR(my_date_column, 'dd/mm/yy hh24:mi:ss')
FROM mytable m

Answer 2

You can use REGEX SUBSTRING function to get the date string on the left.
SELECT REGEXP_SUBSTR (Date_string, '[^,]+', 1, 1)
AS left_part
FROM Table1;
where ^, means look for chars that are NOT comma on 1st position
and get the first occurrence (on the left)
Result:
LEFT_PART
10/11/22 12:14:01
11/12/22 13:15:46
29/12/22 14:30:46
reference:
https://docs.oracle.com/cd/B12037_01/server.101/b10759/functions116.htm

Answer 3

Just do it with the TO_DATE() and TO_CHAR() function pair, both operating on the Oracle date format strings:
Building the scenario:
-- your input ..
WITH indata(dt) AS (
SELECT '10/11/22 12:14:01,807000000' FROM dual UNION ALL
SELECT '11/12/22 13:15:46,650000000' FROM dual UNION ALL
SELECT '29/12/22 14:30:46,501000000' FROM dual
)
-- end of your input. Real query starts here.
-- Change following comma to "WITH" ..
,
-- Now convert to TIMESTAMP(9) ...
as_ts AS (
SELECT
TO_TIMESTAMP(dt ,'DD/MM/YY HH24:MI:SS,FF9') AS ts
FROM indata
)
SELECT
ts
, CAST(ts AS TIMESTAMP(0)) AS recast -- note: this is rounded
, TO_CHAR(ts,'DD/MM/YY HH24:MI:SS') AS reformatted -- this is truncated
FROM as_ts
Result:
TS
RECAST
REFORMATTED
10-NOV-22 12.14.01.807000000
10-NOV-22 12.14.02
10/11/22 12:14:01
11-DEC-22 13.15.46.650000000
11-DEC-22 13.15.47
11/12/22 13:15:46
29-DEC-22 14.30.46.501000000
29-DEC-22 14.30.47
29/12/22 14:30:46

Answer 4

Going by what you have in your question, it appears that the data in the field Date is a timestamp. This isn't a problem, but the names of the table (TABLE) and field (Date) present some challenges.
In Oracle, TABLE is a reserved word - so to use it as the name of a table it must be quoted by putting it inside double-quotes, as "TABLE". Similarly, Date is a mixed-case identifier and must likewise be quoted (e.g. "Date") every time it's used.
Given the above your query becomes:
SELECT TO_CHAR("Date", 'DD/MM/YY HH24:MI:SS') AS FORMATTED_DATE
FROM "TABLE"
and produces the desired results. db<>fiddle here
Generally, it's best in Oracle to avoid using reserved words as identifiers, and to allow the database to convert all names to upper case - if you do that you don't have to quote the names, and you can refer to them by upper or lower case as the database automatically converts all unquoted names to upper case internally.