Oracle Examples

1. Timestamp to readable format

Suppose we have created_timestamp column of type NUMBER(38,0) and represents a Unix timestamp (i.e., number of seconds since 1970-01-01 00:00:00 UTC), we need to convert it to an Oracle TIMESTAMP to make it human-readable.

For values like 1748649600 (10 digits or less)

SELECT
  created_timestamp,
  TO_CHAR(
    (TIMESTAMP '1970-01-01 00:00:00 UTC' + NUMTODSINTERVAL(created_timestamp, 'SECOND')),
    'YYYY-MM-DD HH24:MI:SS'
  ) AS created_readable
FROM your_table;

If created_timestamp is in milliseconds and for values like 1748649600000

SELECT
  created_timestamp,
  TO_CHAR(
    TIMESTAMP '1970-01-01 00:00:00 UTC' +
    NUMTODSINTERVAL(created_timestamp / 1000, 'SECOND'),
    'YYYY-MM-DD HH24:MI:SS'
  ) AS created_readable
FROM your_table;

2. Search records where ext_id has exactly 14 digits

This ensures the ext_id has a length of 14:

If ext_id is a VARCHAR2:

SELECT *
FROM pqr
WHERE LENGTH(ext_id) = 14;

If ext_id is a NUMBER:

SELECT *
FROM pqr
WHERE LENGTH(TO_CHAR(ext_id)) = 14;

3. Ensure ext_id contains only digits 0–9

We can use REGEXP_LIKE to verify the content:

Works for both VARCHAR2 or NUMBER (with conversion):

SELECT *
FROM pqr
WHERE REGEXP_LIKE(TO_CHAR(ext_id), '^[0-9]+$');

4. Create a table with different column types

CLOB

CREATE TABLE my_table (
    id NUMBER,
    text_data CLOB
);

5. Get current timestamp

In Oracle, we can get the current timestamp using the CURRENT_TIMESTAMP function, which returns the current date and time including fractional seconds.

Here’s a basic example:

SELECT CURRENT_TIMESTAMP FROM dual;

If we need a specific format or to use it in a different way, we can use SYSTIMESTAMP as well:

SELECT SYSTIMESTAMP FROM dual;

• CURRENT_TIMESTAMP returns the current timestamp in the session’s timezone.

• SYSTIMESTAMP returns the current timestamp in the database timezone.