DAYS scalar function

The DAYS function returns an integer representation of a date.

The schema is SYSIBM.

expression: An expression that returns a value of one of the following built-in data types: a DATE, TIMESTAMP, or a valid character string representation of a date or timestamp that is not a CLOB. In a Unicode database, if a supplied argument is a graphic string (except DBCLOB), it is first converted to a character string before the function is executed.

The result of the function is a large integer. If the argument can be null, the result can be null; if the argument is null, the result is the null value.

The result is 1 more than the number of days from January 1, 0001 to D, where D is the date that would occur if the DATE function were applied to the argument.

Examples

Example 1: Using the PROJECT table, set the host variable EDUCATION_DAYS (int) to the number of elapsed days (PRENDATE - PRSTDATE) estimated for the project (PROJNO) 'IF2000'.
```
   SELECT DAYS(PRENDATE) - DAYS(PRSTDATE)
     INTO :EDUCATION_DAYS
     FROM PROJECT
     WHERE PROJNO = 'IF2000'
```
Results in EDUCATION_DAYS being set to 396.
Example 2: Using the PROJECT table, set the host variable TOTAL_DAYS (int) to the sum of elapsed days (PRENDATE - PRSTDATE) estimated for all projects in department (DEPTNO) 'E21'.
```
   SELECT SUM(DAYS(PRENDATE) - DAYS(PRSTDATE))
     INTO :TOTAL_DAYS
     FROM PROJECT
     WHERE DEPTNO = 'E21'
```
Results in TOTAL_DAYS being set to 1584 when using the sample table.