TRUNC ON DATE FIELD

TRUNC ( DATAFIELD,'<format>')

Default is 'dd' -- Truncate at the date level , meaning start of the day (Time: 00:00:00)


1. 'dd'  (First hour of the day) 

-- Start of the day

Example:
Select TRUNC(SYSDATE,'dd') from dual;

2. 'mm' (First day of the month) + (First hour of the day)

-- Start of the month

Example:
Select TRUNC(SYSDATE,'mm') from dual;


3. 'yyyy' (First month of the year With First Date) + (First day of the month) + (First hour of the day)

-- Start of the year

Example:
Select TRUNC(SYSDATE,'yyyy') from dual;


4. 'hh' ( Minutes part will be truncated)


 -- Start of the hour

Example:
Select to_char(TRUNC(SYSDATE,'hh'),'mm/dd/yyyy hh24:mi:ss') from dual;

5. 'mi'  (Seconds part will be truncated) 

-- Start of the minute

Example:
Select to_char(TRUNC(SYSDATE,'mi'),'mm/dd/yyyy hh24:mi:ss') from dual;