HOUR

The schema is SYSIBM.

The argument must be an expression that returns a value of one of the following built-in data types: a time, a timestamp, a character string, a graphic string, or a numeric data type.

• If expression is a character or graphic string, it must not be a CLOB or DBCLOB, and its value must be a valid string representation of a time or timestamp with an actual length of not greater than 255 bytes. For the valid formats of string representations of times and timestamps, see String representations of datetime values.
• If expression is a number, it must be a time or timestamp duration. For the valid formats of time and timestamp durations, see Datetime operands.

If expression is a timestamp with a time zone, or a valid string representation of a timestamp with a time zone, the result is determined from the UTC representation of the datetime value.

The result of the function is a large integer.

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 time, timestamp, or string representation of either, the result is the hour part of the value, which is an integer between 1 and 24.
• If the argument is a time duration or timestamp duration, the result is the hour part of the value, which is an integer between -99 and +99. A nonzero result has the same sign as the argument.
• If the argument contains a time zone, the result is the year part of the value expressed in UTC.

   SELECT *
     FROM CLASSES
     WHERE HOUR(STARTTM) > 12;

Example 2: The following invocations of the HOUR function returns the same result:

SELECT HOUR('2003-01-02-20.00.00'), 
			HOUR('2003-01-02-12.00.00-08:00'), 
			HOUR('2003-01-03-05.00.00+09:00') 
		FROM SYSIBM.SYSDUMMY1;

For each invocation of the HOUR function in this SELECT statement, the result is 20.

When the input argument contains a time zone, the result is determined from the UTC representation of the input value. The string representations of a timestamp with a time zone in the SELECT statement all have the same UTC representation: 2003-01-02-20.00.00.