What does this to_date() function of PLSQL do?
سؤال
TO_CHAR(( TO_DATE(calendar_key,'YYYYMMDD' )+ 1),'IW') week
Can somebody tell me what's happening in this query? I know what the to_date operation does, I am confused about the '+1' over there, does it add 1 year to the date??
And what about the 'IW'? Is it alias name? and then why 'week'?
Plese help me. Thanks in advance
المحلول
1) When using basic arithmetics on dates - it operates with days. So +1
means add one day
How could you figure it out yourself:
SELECT systimestamp, systimestamp + 1 FROM DUAL
2) http://docs.oracle.com/cd/B19306_01/server.102/b14200/sql_elements004.htm#i34948
IW - Week of year (1-52 or 1-53) based on the ISO standard.
How could you figure it out yourself:
Google for: "oracle to_char"
PS:
Is it alias name?
Aliases cannot be enclosed by single quotes by definition: they may be placed inside of double quotes or without quotes around at all. So if you see something put in single quotes - it is definitely a string literal.