Oracle SQL how to remove time from date

TRUNC: the date-time butcher

Our hero function TRUNC comes to rescue. This Oracle SQL function is a workhorse. When it encounters a date, TRUNC cleanly slices off the time, reducing it to the Cinderella hour - 00:00:00. What's left is a neat date, ready for comparison, aggregation, or simply decluttering your life. Adios, time clutter!

Date masquerading as a VARCHAR2

Sometimes, dates dress up as VARCHAR2 strings. In such impostor situations, a two-step process is required. First, unmask the date using TO_DATE and the correct format mask**. Then apply **TRUNC`:

-- Unmasking the date in disguise
SELECT TRUNC(TO_DATE(varchar_date_col, 'YYYY-MM-DD HH24:MI:SS')) FROM table;
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Remember, strings posing as dates are controversial in SQL society. Such masquerades can lead to complex date operations and a significant performance hit parade. So avoid them when you can!

Dealing with format landmines

Stepping on an unexpected date format can cause your precious SQL script to blow up. NLS_DATE_FORMAT setting impacts how your TO_CHAR formatted dates look and behave. So before you step on a rake, make sure the field is clear:

-- Cleaning up the field
ALTER SESSION SET NLS_DATE_FORMAT = 'YYYY-MM-DD';
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What if you still step on a formatting landmine? Enter VALIDATE_CONVERSION(), Oracle 12c's bomb disposal squad. Save yourself from head-banging runtime errors:

-- Bomb disposal squad to the rescue
SELECT date_col FROM table
WHERE VALIDATE_CONVERSION(date_col AS DATE, 'YYYY-MM-DD') = 1;
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Mastering the date manipulation

While working with TRUNC and TO_DATE, train your eyes on your data types. Even a flyweight data type mismatch can pack a heavyweight punch. So keep it tidy, folks. Before you go and share your brilliant work, pass it through the filter of sample data tests. Keep your script tight. Suit it up for your date column requirements and business logic.