DAY scalar function

The DAY function returns the day part of a value.

The schema is SYSIBM.

expression

An expression that returns a value of one of the following built-in data types: DATE, TIMESTAMP, numeric, or character string that is not a CLOB.

If the value is a number, it must be a date duration or timestamp duration (SQLSTATE 42815).

If the value is a character string, it must be a valid string representation of a date or timestamp. In a Unicode database, if the value 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 other rules depend on the data type of the argument:

If the argument is a DATE, TIMESTAMP, or valid string representation of a date or timestamp:
- The result is the day part of the value, which is an integer between 1 and 31.
If the argument is a date duration or timestamp duration:
- The result is the day part of the value, which is an integer between -99 and 99. A nonzero result has the same sign as the argument.

Examples

Example 1: Using the PROJECT table, set the host variable END_DAY (smallint) to the day that the WELD LINE PLANNING project (PROJNAME) is scheduled to stop (PRENDATE).
```
   SELECT DAY(PRENDATE)
     INTO :END_DAY
     FROM PROJECT
     WHERE PROJNAME = 'WELD LINE PLANNING'
```
Results in END_DAY being set to 15 when using the sample table.
Example 2: Assume that the column DATE1 (whose data type is DATE) has an internal value equivalent to 2000-03-15 and the column DATE2 (whose data type is DATE) has an internal value equivalent to 1999-12-31.
```
   DAY(DATE1 - DATE2)
```
Results in the value 15.