DAYS function [Date and time]

A function that evaluates days. For specific details, see this function's usage.

Syntax 1: integer

DAYS( [ datetime-expression, ] datetime-expression )

Syntax 2: timestamp

DAYS( datetime-expression, integer-expression )

Parameters

datetime-expression A date and time.
integer-expression The number of days to be added to the datetime-expression. If the integer-expression is negative, the appropriate number of days is subtracted from the timestamp. If you supply an integer expression, the datetime-expression must be explicitly cast as a date or timestamp.
For information about casting data types, see CAST function [Data type conversion].

Remarks

The behavior of this function can vary depending on what you supply:

If you give a single date, this function returns the number of days since 0000-02-29.

Note

0000-02-29 is not meant to imply an actual date; it is the date used by the date algorithm.
If you give two dates, this function returns the integer number of days between them. Instead, use the DATEDIFF function.
If you give a date and an integer, this function adds the integer number of days to the specified date. Instead, use the DATEADD function.

This function ignores hours, minutes, and seconds.

Standards and compatibility

SQL/2003 Vendor extension.

Example

The following statement returns the integer 729889.

SELECT DAYS( '1998-07-13 06:07:12' );

The following statements return the integer value -366, indicating that the second date is 366 days prior to the first. It is recommended that you use the second example (DATEDIFF).

SELECT DAYS( '1998-07-13 06:07:12',
             '1997-07-12 10:07:12' );

SELECT DATEDIFF( day,
   '1998-07-13 06:07:12',
   '1997-07-12 10:07:12' );

The following statements return the timestamp 1999-07-14 00:00:00.000. It is recommended that you use the second example (DATEADD).

SELECT DAYS( CAST('1998-07-13' AS DATE ), 366 );

SELECT DATEADD( day, 366, '1998-07-13' );

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