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--- dev:sql:functions:calc_date [2009/12/18 15:22]
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+++ dev:sql:functions:calc_date [2010/07/27 17:43]
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-<html><div align="center"><span style="color:red">DRAFT</span></div></html>
-====== Omnidex SQL Function: $CALC_DATE ======
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+====== Omnidex SQL Function: $CALC_DATE ======
 ===== Description =====
+The $CALC_DATE function performs arithmetic on a date expression, returning a new date value.  The arithmetic is performed using the units declared in the function, or using DAYS if not specified.
-$CALC_DATE calculates a new date from a specified date or column_date using a numeric positive or negative offset.  The offset defaults to days but can be changed by using the date_unit optional argument.
+This function returns the same datatype as the passed date expression.
 ===== Syntax =====
-Result = $calc_date( <date_column | 'date_string' >, offset [, date_unit [, options])
+  $CALC_DATE( date_expression, numeric_expression [ , date_token ] )
-Returns a floating point value.
-===== Discussion =====
+== date_expression ==
-== <date_column_spec | 'date_string' > ==
-An expression resulting in date-class or string-class datatype.
+Required. Any expression that returns a date-class datatype. Examples of date expressions are columns or functions that return a date-class datatype.  The date-class datatypes are any of the date or time oriented datatypes found in the list of [[dev:appendix:reference:datatypes|Omnidex datatypes]].
-== value_expression ==
-An expression resulting in a numeric-class (integer or floating point) value.
-Negative values supported.
+== numeric_expression ==
-== date_unit ==
-A string containing unit abbreviation that tell the $calc_date function to add or subtract the number of date_units.
+Required. Any expression that returns a numeric-class datatype. Examples of numeric expressions are columns, functions or expressions that return a numeric-class datatype.  The numeric datatypes are found in the list of [[dev:appendix:reference:datatypes|Omnidex datatypes]].
-Valid datefield Options:
+If this function is to return a date in the future, the numeric expression should return a positive value.  If this function is to return a date in the past, the numeric expression should return a negative value.
-^ Date_field ^ Description ^
-| YEAR | Year |
+== date_token ==
-| MONTH | Month |
-| DAY | Day |
+Optional. One of the following tokens representing the unit for the date arithmetic.
-| HOUR | Hour |
-| MINUTE | Minute |
+{{page>dev:appendix:reference:date_tokens_insert&noheader&nofooter&noeditbtn}}
-| SECOND | Second |
-| W | Day of the week number (1-Sunday, 2-Monday) |
-| WW | Three-character day-of-week abbreviation (Sun, Mon) |
+== date_column ==
-| WWW | Fully spelled day-of-week (Sunday, Monday) |
-| M | Non-zero-filled month number (1-January, 2-February) |
+Required. A column that is declared as a date_class datatype.  The date_class datatypes are any of the date or time oriented datatypes found in the list of [[dev:appendix:reference:datatypes|Omnidex datatypes]].
-| 0M | Zero-filled day-of-month number (01-January, 02-February) |
-| MM | Three-character month abbreviation (Jan, Feb) |
-| MMM | Fully spelled month (January, February) |
-| D | Non-zero-filled day-of-month (1, 2, 3) |
-| 0D | Zero-filled day-of-month (01, 02, 03) |
-| J | Non-zero-filled Julian date (1, 2) |
-| 0J | Zero-filled Julian date (01, 02) |
-| YY | Two-digit year (99, 00) |
-| YYYY | Four-digit year (1999, 2000) |
-| H | 12-hour, non-zero-filled hour of day (12, 1) |
-| 0H | 12-hour, zero-filled hour of day (12, 01) |
-| HH | 24-hour, non-zero-filled hour of day (24, 1) |
-| 0HH | 24-hour, zero-filled hour of day (24, 01) |
-| N | Non-zero-filled minute of hour (1, 2) |
-| 0N | Zero-filled minute of hour (01, 02) |
-| S | Non-zero-filled second of minute (1, 2) |
-| 0S | Zero-filled second of minute (01, 02) |
-| F | Non-zero-filled fraction of a second (1, 2) |
-| 0F | Zero-filled fraction of a second (01, 02) |
-| A | Lowercase am/pm indicator |
-| AA | Uppercase AM/PM indicator |
-== Options ==
-There are no options currently for this function.
 ===== Example =====
-==== Example 1 ====
+==== Example 1: $CALC_DATE adding 18 years ====
 <code>
-> select $calc_date('20090101', -5) from $omnidex
+> select birthdate, $calc_date(birthdate, 18, 'YY') bday_plus_18 from individuals;
-$CALC_DATE('20090101',
+BIRTHDATE     BDAY_PLUS_18
-----------------------
+------------  ------------
--12-27
+-07-14    1956-07-14
+-11-22    1975-11-22
+-07-28    1978-07-28
+-08-22    1947-08-22
+-07-09    1951-07-09
+-08-01    1962-08-01
+-09-14    2022-09-14
 </code>
-==== Example 2 ====
-<code>
-> select $calc_date('20090101', -5,YEAR) from $omnidex
-$CALC_DATE('20090101',
+====== Additional Resources ======
-----------------------
--01-01
+See also:
+{{page>dev:sql:functions:see_also_dates&noheader&nofooter&noeditbtn}}
-</code>
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dev/sql/functions/calc_date.txt · Last modified: 2016/06/28 22:38 (external edit)

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