Add information regarding date and time types and functions,

including arguments allowed.

src/man/built-in.3

@@ -1,6 +1,6 @@
 .\" This is -*-nroff-*-
 .\" XXX standard disclaimer belongs here....
-.\" $Header: /cvsroot/pgsql/src/man/Attic/built-in.3,v 1.7 1997/05/16 07:13:46 thomas Exp $
+.\" $Header: /cvsroot/pgsql/src/man/Attic/built-in.3,v 1.8 1997/07/02 14:13:14 thomas Exp $
 .TH BUILT-INS INTRO 04/01/97 PostgreSQL PostgreSQL
 .SH "DESCRIPTION"
 This section describes the data types, functions and operators
@@ -82,7 +82,11 @@ several possibilities for formats, such as date and time types.
 Some date and time types share code for data input. For those types (currently
 .IR datetime
 and
-.IR abstime )
+.IR abstime
+, and
+.IR timespan
+and
+.IR reltime )
 the input can have any of a wide variety of styles. For numeric date representations,
 European and US conventions can differ, and the proper interpretation is obtained
 by using the
@@ -129,22 +133,22 @@ offsets to GMT (e.g. "-08" or "-08:00" when in Pacific Standard Time).
 Dates are stored internally in Greenwich Mean Time. Input and output routines 
 translate time to the local time zone of the server.
 .PP
-All special values allowed for
+The special values `current',
-.IR "absolute time"
+`infinity' and `-infinity' are provided.
-are also allowed for
+`infinity' specifies a time later than any valid time, and
-.IR "datetime".
+`-infinity' specifies a time earlier than any valid time.
-The special values \*(lqcurrent\*(rq,
+`current' indicates that the current time should be
-\*(lqinfinity\*(rq and \*(lq-infinity\*(rq are provided.
-\*(lqinfinity\*(rq specifies a time later than any valid time, and
-\*(lq-infinity\*(rq specifies a time earlier than any valid time.
-\*(lqcurrent\*(rq indicates that the current time should be
 substituted whenever this value appears in a computation.
 .PP
-The strings \*(lqnow\*(rq and \*(lqepoch\*(rq can be used to specify
+The strings
-time values.  \*(lqnow\*(rq means the current time, and differs from
+`now',
-\*(lqcurrent\*(rq in that the current time is immediately substituted
+`today',
-for it.  \*(lqepoch\*(rq means Jan 1 00:00:00 1970 GMT.
+`yesterday',
-
+`tomorrow',
+and `epoch' can be used to specify
+time values.  `now' means the current time, and differs from
+`current' in that the current time is immediately substituted
+for it.  `epoch' means Jan 1 00:00:00 1970 GMT.
 
 .SH "TIMESPAN"
 General-use time span is input using a wide range of
@@ -165,10 +169,10 @@ Time span is specified with the following syntax:
 @ Quantity Unit [Direction]
 .sp
 where 	
-	Quantity is ..., '-1', '0', `1', `2', ...
+	Quantity is ..., `-1', `0', `1', `2', ...
 	Unit is `second', `minute', `hour', `day', `week', `month', `year',
 	or abbreviations or plurals of these units.
-	Direction is ``ago''
+	Direction is `ago'.
 .fi
 .SH "ABSOLUTE TIME"
 Absolute time (abstime) is a limited-range (+/- 68 years) and limited-precision (1 sec)
@@ -196,17 +200,10 @@ Valid dates are from Dec 13 20:45:53 1901 GMT to Jan 19 03:14:04
 using Greenwich Mean Time; the input and output routines default to
 the local time zone.
 .PP
-The special absolute time values \*(lqcurrent\*(rq,
+All special values allowed for
-\*(lqinfinity\*(rq and \*(lq-infinity\*(rq are also provided.
+.IR "datetime"
-\*(lqinfinity\*(rq specifies a time later than any valid time, and
+are also allowed for
-\*(lq-infinity\*(rq specifies a time earlier than any valid time.
+.IR "absolute time".
-\*(lqcurrent\*(rq indicates that the current time should be
-substituted whenever this value appears in a computation.
-.PP
-The strings \*(lqnow\*(rq and \*(lqepoch\*(rq can be used to specify
-time values.  \*(lqnow\*(rq means the current time, and differs from
-\*(lqcurrent\*(rq in that the current time is immediately substituted
-for it.  \*(lqepoch\*(rq means Jan 1 00:00:00 1970 GMT.
 
 .SH "RELATIVE TIME"
 Relative time (reltime) is a limited-range (+/- 68 years) and limited-precision (1 sec)
@@ -506,6 +503,16 @@ tinterval
 .SH "FUNCTIONS"
 Many data types have functions available for conversion to other related types.
 In addition, there are some type-specific functions.
+.PP
+For the
+date_part() and date_trunc()
+functions, arguments can be
+`year', `month', `day', `hour', `minute', and `second',
+as well as the more specialized quantities
+`decade', `century', `millenium', `millisecond', and `microsecond'.
+date_part() also allows
+`dow'
+to return day of week and `epoch' to return seconds since 1970.
 
 .nf
 Functions:
@@ -521,6 +528,7 @@ date
 datetime
 	abstime  abstime(datetime)         convert to abstime
 	float8   date_part(text,datetime)  specified portion of date field
+	datetime date_trunc(text,datetime) truncate date at specified units
 	bool     isfinite(datetime)        TRUE if this is a finite time
 
 reltime
@@ -550,6 +558,7 @@ circle
 	float8   diameter(circle)          diameter of circle
 	float8   area(circle)              area of circle
 .fi
+
 .SH "BINARY OPERATORS"
 This list was generated from the Postgres system catalogs with the
 query: