New moddatetime contrib from Terry Mackintosh.

diff --git a/contrib/spi/Makefile b/contrib/spi/Makefile
index 6bb634aa7703285a09464a4fcf44fd13d201f04b..c9c9ff8d48058e91354add20a0c13edb678816b1 100644 (file)
--- a/contrib/spi/Makefile
+++ b/contrib/spi/Makefile
@@ -12,7 +12,7 @@ CFLAGS+= -DREFINT_VERBOSE
 endif
 
 TARGETS= refint$(DLSUFFIX) refint.sql timetravel$(DLSUFFIX) timetravel.sql \
-       autoinc$(DLSUFFIX) autoinc.sql \
+       autoinc$(DLSUFFIX) autoinc.sql moddatetime$(DLSUFFIX) moddatetime.sql \
        insert_username$(DLSUFFIX) insert_username.sql
 
 CLEANFILES+= $(TARGETS)

diff --git a/contrib/spi/moddatetime.c b/contrib/spi/moddatetime.c
new file mode 100644 (file)
index 0000000..a6ef3b2
--- /dev/null
+++ b/contrib/spi/moddatetime.c
@@ -0,0 +1,106 @@
+/*
+moddatetime.c
+
+What is this?
+It is a function to be called from a trigger for the perpose of updating
+a modification datetime stamp in a record when that record is UPDATEd.
+
+Credits
+This is 95%+ based on autoinc.c, which I used as a starting point as I do
+not really know what I am doing.  I also had help from 
+Jan Wieck <jwieck@debis.com> who told me about the datetime_in("now") function.
+OH, me, I'm Terry Mackintosh <terry@terrym.com>
+*/
+
+#include "executor/spi.h"      /* this is what you need to work with SPI */
+#include "commands/trigger.h"  /* -"- and triggers */
+
+HeapTuple  moddatetime(void);
+
+HeapTuple moddatetime()
+{
+   Trigger     *trigger;       /* to get trigger name */
+   int         nargs;          /* # of arguments */
+   int         attnum;         /* positional number of field to change */
+   Datum           newdt;          /* The current datetime. */
+   char            **args;         /* arguments */
+   char            *relname;       /* triggered relation name */
+   Relation        rel;                /* triggered relation */
+   HeapTuple   rettuple = NULL;
+   TupleDesc   tupdesc;            /* tuple description */
+
+   if (!CurrentTriggerData)
+       elog(ERROR, "moddatetime: triggers are not initialized.");
+
+   if (TRIGGER_FIRED_FOR_STATEMENT(CurrentTriggerData->tg_event))
+       elog(ERROR, "moddatetime: can't process STATEMENT events.");
+
+   if (TRIGGER_FIRED_AFTER(CurrentTriggerData->tg_event))
+       elog(ERROR, "moddatetime: must be fired before event.");
+
+   if (TRIGGER_FIRED_BY_INSERT(CurrentTriggerData->tg_event))
+       elog(ERROR, "moddatetime: must be fired before event.");
+   else if (TRIGGER_FIRED_BY_UPDATE(CurrentTriggerData->tg_event))
+       rettuple = CurrentTriggerData->tg_newtuple;
+   else
+       elog(ERROR, "moddatetime: can't process DELETE events.");
+
+   rel = CurrentTriggerData->tg_relation;
+   relname = SPI_getrelname(rel);
+
+   trigger = CurrentTriggerData->tg_trigger;
+
+   nargs = trigger->tgnargs;
+
+   if (nargs != 1)
+       elog(ERROR, "moddatetime (%s): A single argument was expected.", relname);
+
+   args = trigger->tgargs;
+   /* must be the field layout? */
+   tupdesc = rel->rd_att;
+
+   /* Why do this? */
+   CurrentTriggerData = NULL;
+
+   /* Get the current datetime. */
+   newdt = datetime_in("now");
+
+   /* This gets the position in the turple of the field we want.
+       args[0] being the name of the field to update, as passed in
+       from the trigger.
+   */
+   attnum = SPI_fnumber(tupdesc, args[0]);
+
+   /* This is were we check to see if the feild we are suppost to update even
+       exits.  The above function must return -1 if name not found?
+   */
+   if (attnum < 0)
+       elog(ERROR, "moddatetime (%s): there is no attribute %s", relname,
+           args[0]);
+           
+   /* OK, this is where we make sure the datetime field that we are 
+       modifying is really a datetime field.
+       Hay, error checking, what a novel idea !-)
+   */
+   if (SPI_gettypeid(tupdesc, attnum) != DATETIMEOID )
+       elog(ERROR, "moddatetime (%s): attribute %s must be of DATETIME type",
+            relname, args[0]);
+
+/* 1 is the number of items in the arrays attnum and newdt. 
+   attnum is the positional number of the field to be updated.
+   newdt is the new datetime stamp.
+   NOTE that attnum and newdt are not arrays, but then a 1 ellement array
+   is not an array any more then they are.  Thus, they can be considered a
+   one element array.
+*/
+   rettuple = SPI_modifytuple(rel, rettuple, 1, &attnum, &newdt, NULL);
+
+   if (rettuple == NULL)
+       elog(ERROR, "moddatetime (%s): %d returned by SPI_modifytuple",
+            relname, SPI_result);
+
+/* Clean up */
+   pfree(relname);
+
+   return (rettuple);
+}

diff --git a/contrib/spi/moddatetime.example b/contrib/spi/moddatetime.example
new file mode 100644 (file)
index 0000000..25a54e3
--- /dev/null
+++ b/contrib/spi/moddatetime.example
@@ -0,0 +1,27 @@
+DROP TABLE mdt;
+
+CREATE TABLE mdt (
+   id      int4,
+   idesc       text,
+   moddate datetime DEFAULT datetime(CURRENT_TIMESTAMP) NOT NULL
+);
+
+CREATE TRIGGER mdt_moddatetime
+   BEFORE UPDATE ON mdt
+   FOR EACH ROW 
+   EXECUTE PROCEDURE moddatetime (moddate);
+
+INSERT INTO mdt VALUES (1, 'first');
+INSERT INTO mdt VALUES (2, 'second');
+INSERT INTO mdt VALUES (3, 'third');
+
+SELECT * FROM mdt;
+
+UPDATE mdt SET id = 4
+   WHERE id = 1;
+UPDATE mdt SET id = 5
+   WHERE id = 2;
+UPDATE mdt SET id = 6
+   WHERE id = 3;
+
+SELECT * FROM mdt;

diff --git a/contrib/spi/moddatetime.source b/contrib/spi/moddatetime.source
new file mode 100644 (file)
index 0000000..26906a3
--- /dev/null
+++ b/contrib/spi/moddatetime.source
@@ -0,0 +1,6 @@
+DROP FUNCTION moddatetime();
+
+CREATE FUNCTION moddatetime() 
+   RETURNS opaque 
+   AS '_OBJWD_/moddatetime_DLSUFFIX_'
+   LANGUAGE 'c';