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dateinformixextend

What is the difference between CURRENT and TODAY in Informix

I am junior in informix and I am struggling with some date calculations. I have this code snippet in my source:

LET dtRefDate = TODAY;

IF extend( CURRENT, hour to hour ) BETWEEN '06' AND '23'  THEN LET
   dtRefDate = TODAY+1;
END IF;

Can anybody explain me please what does extend function do? and what is the difference between CURRENT and TODAY? I didn't comprehend the difference from IBM official documentation. Thank you

Solution

  • TODAY returns a DATE value, CURRENT returns a DATETIME (YEAR TO FRACTION (3)) value.

    EXTEND is used to extract individual parts of a DATE or DATETIME value.

    Look at this examples:

    > select CURRENT from table(set{1});
(expression)
2019-09-29 10:07:12.000
1 row(s) retrieved.

> select TODAY from table(set{1});
(expression)
09/29/2019
1 row(s) retrieved.

> select extend(TODAY,year to year) from table(set{1});
(expression)
2019
1 row(s) retrieved.

> select extend(TODAY,month to day) from table(set{1});
(expression)
09-29
1 row(s) retrieved.

> select extend(CURRENT,hour to minute) from table(set{1});
(expression)
10:08
1 row(s) retrieved.

>