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contrib/datetime/datetime_functions.c

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+/*
+ * datetime_functions.c --
+ *
+ * This file defines new functions for the time and date data types.
+ *
+ * Copyright (c) 1996, Massimo Dal Zotto <dz@cs.unitn.it>
+ */
+
+#include <time.h>
+
+#include "postgres.h"
+#include "pg_type.h"
+#include "utils/palloc.h"
+
+typedef struct DateADT {
+    char	day;
+    char	month;
+    short	year;
+} DateADT;
+
+typedef struct TimeADT {
+    short	hr;
+    short	min;
+    float	sec;
+} TimeADT;
+
+TimeADT *
+time_difference(TimeADT *time1, TimeADT *time2)
+{
+    TimeADT *time = (TimeADT*)palloc(sizeof(TimeADT));
+
+    time->sec = time1->sec - time2->sec;
+    time->min = time1->min - time2->min;
+    time->hr  = time1->hr  - time2->hr;
+
+    if (time->sec < 0) {
+	time->sec += 60.0;
+	time->min--;
+    } else if (time->sec >= 60.0) {
+	time->sec -= 60.0;
+	time->min++;
+    }
+
+    if (time->min < 0) {
+	time->min += 60;
+	time->hr--;
+    } else if (time->min >= 60) {
+	time->min -= 60;
+	time->hr++;
+    }
+
+    if (time->hr < 0) {
+	time->hr += 24;
+    } else if (time->hr >= 24) {
+	time->hr -= 24;
+    }
+
+    return (time);
+}
+
+TimeADT *
+currentTime()
+{
+    time_t current_time;
+    struct tm *tm;
+    TimeADT *result = (TimeADT*)palloc(sizeof(TimeADT));
+
+    current_time = time(NULL);
+    tm = localtime(&current_time);
+    result->sec = tm->tm_sec;
+    result->min = tm->tm_min;
+    result->hr  = tm->tm_hour;
+
+    return (result);
+}
+
+int4
+currentDate()
+{
+    time_t current_time;
+    struct tm *tm;
+    int4 result;
+    DateADT *date = (DateADT*)&result;
+
+    current_time = time(NULL);
+    tm = localtime(&current_time);
+    date->day   = tm->tm_mday;
+    date->month = tm->tm_mon+1;
+    date->year  = tm->tm_year+1900;
+
+    return (result);
+}
+
+int4
+hours(TimeADT *time)
+{
+    return (time->hr);
+}
+
+int4
+minutes(TimeADT *time)
+{
+    return (time->min);
+}
+
+int4
+seconds(TimeADT *time)
+{
+    int seconds = (int)time->sec;
+    return (seconds);
+}
+
+int4
+day(int4 val)
+{
+    DateADT *date = (DateADT*)&val;
+    return (date->day);
+}
+
+int4
+month(int4 val)
+{
+    DateADT *date = (DateADT*)&val;
+    return (date->month);
+}
+
+int4
+year(int4 val)
+{
+    DateADT *date = (DateADT*)&val;
+    return (date->year);
+}
+
+int4
+asMinutes(TimeADT *time)
+{
+    int seconds = (int)time->sec;
+    return (time->min + 60*time->hr);
+}
+
+int4
+asSeconds(TimeADT *time)
+{
+    int seconds = (int)time->sec;
+    return (seconds + 60*time->min + 3600*time->hr);
+}
+

contrib/datetime/datetime_functions.doc

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+From: Massimo Dal Zotto <dz@cs.unitn.it>
+Date: Tue, 14 May 1996 14:31:18 +0200 (MET DST)
+Subject: [PG95]: new postgres functions
+
+- -----BEGIN PGP SIGNED MESSAGE-----
+
+Some time ago I read in the mailing list requests of people looking
+for more time and date functions.  I have now written some of them:
+
+  time_difference(time1, time2) ,also defined as operator '-'
+  hour(time)
+  minutes(time)
+  seconds(time)
+  asMinutes(time)
+  asSeconds(time)
+  currentTime()
+  currentDate()
+
+The file can be compiled as shared library and loaded as dynamic module
+without need to recompile the backend.  This can also be taken as an example
+of the extensibility of postgres (user-defined functions, operators, etc).
+I would be nice to see more of these user contributed modules posted to this
+list and hopefully accessible from the Postgres home page.
+
+

contrib/datetime/datetime_functions.sql

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+
+-- SQL code to load and define 'datetime' functions
+
+-- load the new functions
+
+load '/home/dz/lib/postgres/datetime_functions.so';
+
+-- define the new functions in postgres
+
+create function time_difference(time,time)
+  returns time
+  as '/home/dz/lib/postgres/datetime_functions.so' 
+  language 'c';
+
+create function currentDate()
+  returns date
+  as '/home/dz/lib/postgres/datetime_functions.so' 
+  language 'c';
+
+create function currentTime()
+  returns time
+  as '/home/dz/lib/postgres/datetime_functions.so' 
+  language 'c';
+
+create function hours(time)
+  returns int4
+  as '/home/dz/lib/postgres/datetime_functions.so' 
+  language 'c';
+
+create function minutes(time)
+  returns int4
+  as '/home/dz/lib/postgres/datetime_functions.so' 
+  language 'c';
+
+create function seconds(time)
+  returns int4
+  as '/home/dz/lib/postgres/datetime_functions.so' 
+  language 'c';
+
+create function day(date)
+  returns int4
+  as '/home/dz/lib/postgres/datetime_functions.so'
+  language 'c';
+
+create function month(date)
+  returns int4
+  as '/home/dz/lib/postgres/datetime_functions.so'
+  language 'c';
+
+create function year(date)
+  returns int4
+  as '/home/dz/lib/postgres/datetime_functions.so'
+  language 'c';
+
+create function asMinutes(time)
+  returns int4
+  as '/home/dz/lib/postgres/datetime_functions.so' 
+  language 'c';
+
+create function asSeconds(time)
+  returns int4
+  as '/home/dz/lib/postgres/datetime_functions.so' 
+  language 'c';
+
+create operator - (
+  leftarg=time, 
+  rightarg=time, 
+  procedure=time_difference);
+