Fix datetime input parsing to accept YYYY-MONTHNAME-DD and related syntaxes,

which had been unintentionally broken by recent changes to tighten up the
DateStyle rules for all-numeric date input.  Add documentation and
regression tests for this, too.

doc/src/sgml/datatype.sgml

 <!--
-$Header: /cvsroot/pgsql/doc/src/sgml/datatype.sgml,v 1.130 2003/11/06 22:21:47 tgl Exp $
+$Header: /cvsroot/pgsql/doc/src/sgml/datatype.sgml,v 1.131 2003/11/16 20:29:16 tgl Exp $
 -->
 
  <chapter id="datatype">
@@ -1464,7 +1464,7 @@ SELECT b, char_length(b) FROM test2;
         </row>
         <row>
          <entry>1999-01-08</entry>
-         <entry>ISO 8601, January 8 in any mode
+         <entry>ISO 8601; January 8 in any mode
          (recommended format)</entry>
         </row>
         <row>
@@ -1484,6 +1484,30 @@ SELECT b, char_length(b) FROM test2;
           February 3, 2001 in <literal>YMD</> mode
          </entry>
         </row>
+        <row>
+         <entry>1999-Jan-08</entry>
+         <entry>January 8 in any mode</entry>
+        </row>
+        <row>
+         <entry>Jan-08-1999</entry>
+         <entry>January 8 in any mode</entry>
+        </row>
+        <row>
+         <entry>08-Jan-1999</entry>
+         <entry>January 8 in any mode</entry>
+        </row>
+        <row>
+         <entry>99-Jan-08</entry>
+         <entry>January 8 in <literal>YMD</> mode, else error</entry>
+        </row>
+        <row>
+         <entry>08-Jan-99</entry>
+         <entry>January 8, except error in <literal>YMD</> mode</entry>
+        </row>
+        <row>
+         <entry>Jan-08-99</entry>
+         <entry>January 8, except error in <literal>YMD</> mode</entry>
+        </row>
         <row>
          <entry>19990108</entry>
          <entry>ISO 8601; January 8, 1999 in any mode</entry>
@@ -1625,7 +1649,7 @@ SELECT b, char_length(b) FROM test2;
          </row>
          <row>
           <entry><literal>zulu</literal></entry>
-          <entry>Military abbreviation for GMT</entry>
+          <entry>Military abbreviation for UTC</entry>
          </row>
          <row>
           <entry><literal>z</literal></entry>

src/backend/utils/adt/datetime.c

@@ -8,7 +8,7 @@
  *
  *
  * IDENTIFICATION
- *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/datetime.c,v 1.118 2003/09/25 06:58:03 petere Exp $
+ *	  $Header: /cvsroot/pgsql/src/backend/utils/adt/datetime.c,v 1.119 2003/11/16 20:29:16 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -25,7 +25,7 @@
 #include "utils/guc.h"
 
 
-static int DecodeNumber(int flen, char *field,
+static int DecodeNumber(int flen, char *field, bool haveTextMonth,
 			 int fmask, int *tmask,
 			 struct tm * tm, fsec_t *fsec, int *is2digits);
 static int DecodeNumberField(int len, char *str,
@@ -924,7 +924,7 @@ DecodeDateTime(char **field, int *ftype, int nf,
 	int			val;
 	int			dterr;
 	int			mer = HR24;
-	int			haveTextMonth = FALSE;
+	bool		haveTextMonth = FALSE;
 	int			is2digits = FALSE;
 	int			bc = FALSE;
 
@@ -1281,7 +1281,8 @@ DecodeDateTime(char **field, int *ftype, int nf,
 					/* otherwise it is a single date/time field... */
 					else
 					{
-						dterr = DecodeNumber(flen, field[i], fmask,
+						dterr = DecodeNumber(flen, field[i],
+											 haveTextMonth, fmask,
 											 &tmask, tm,
 											 fsec, &is2digits);
 						if (dterr)
@@ -2032,6 +2033,7 @@ DecodeTimeOnly(char **field, int *ftype, int nf,
 					else
 					{
 						dterr = DecodeNumber(flen, field[i],
+											 FALSE,
 											 (fmask | DTK_DATE_M),
 											 &tmask, tm,
 											 fsec, &is2digits);
@@ -2229,6 +2231,7 @@ DecodeDate(char *str, int fmask, int *tmask, struct tm * tm)
 	int			i,
 				len;
 	int			dterr;
+	bool		haveTextMonth = FALSE;
 	int			bc = FALSE;
 	int			is2digits = FALSE;
 	int			type,
@@ -2283,6 +2286,7 @@ DecodeDate(char *str, int fmask, int *tmask, struct tm * tm)
 			{
 				case MONTH:
 					tm->tm_mon = val;
+					haveTextMonth = TRUE;
 					break;
 
 				case ADBC:
@@ -2312,7 +2316,7 @@ DecodeDate(char *str, int fmask, int *tmask, struct tm * tm)
 		if ((len = strlen(field[i])) <= 0)
 			return DTERR_BAD_FORMAT;
 
-		dterr = DecodeNumber(len, field[i], fmask,
+		dterr = DecodeNumber(len, field[i], haveTextMonth, fmask,
 							 &dmask, tm,
 							 &fsec, &is2digits);
 		if (dterr)
@@ -2444,7 +2448,7 @@ DecodeTime(char *str, int fmask, int *tmask, struct tm * tm, fsec_t *fsec)
  * Return 0 if okay, a DTERR code if not.
  */
 static int
-DecodeNumber(int flen, char *str, int fmask,
+DecodeNumber(int flen, char *str, bool haveTextMonth, int fmask,
 			 int *tmask, struct tm * tm, fsec_t *fsec, int *is2digits)
 {
 	int			val;
@@ -2534,10 +2538,59 @@ DecodeNumber(int flen, char *str, int fmask,
 			tm->tm_mon = val;
 			break;
 
+		case (DTK_M(MONTH)):
+			if (haveTextMonth)
+			{
+				/*
+				 * We are at the first numeric field of a date that included
+				 * a textual month name.  We want to support the variants
+				 * MON-DD-YYYY, DD-MON-YYYY, and YYYY-MON-DD as unambiguous
+				 * inputs.  We will also accept MON-DD-YY or DD-MON-YY in
+				 * either DMY or MDY modes, as well as YY-MON-DD in YMD mode.
+				 */
+				if (flen >= 3 || DateOrder == DATEORDER_YMD)
+				{
+					*tmask = DTK_M(YEAR);
+					tm->tm_year = val;
+				}
+				else
+				{
+					*tmask = DTK_M(DAY);
+					tm->tm_mday = val;
+				}
+			}
+			else
+			{
+				/* Must be at second field of MM-DD-YY */
+				*tmask = DTK_M(DAY);
+				tm->tm_mday = val;
+			}
+			break;
+
 		case (DTK_M(YEAR) | DTK_M(MONTH)):
-			/* Must be at third field of YY-MM-DD */
-			*tmask = DTK_M(DAY);
-			tm->tm_mday = val;
+			if (haveTextMonth)
+			{
+				/* Need to accept DD-MON-YYYY even in YMD mode */
+				if (flen >= 3 && *is2digits)
+				{
+					/* Guess that first numeric field is day was wrong */
+					*tmask = DTK_M(DAY); /* YEAR is already set */
+					tm->tm_mday = tm->tm_year;
+					tm->tm_year = val;
+					*is2digits = FALSE;
+				}
+				else
+				{
+					*tmask = DTK_M(DAY);
+					tm->tm_mday = val;
+				}
+			}
+			else
+			{
+				/* Must be at third field of YY-MM-DD */
+				*tmask = DTK_M(DAY);
+				tm->tm_mday = val;
+			}
 			break;
 
 		case (DTK_M(DAY)):
@@ -2552,12 +2605,6 @@ DecodeNumber(int flen, char *str, int fmask,
 			tm->tm_year = val;
 			break;
 
-		case (DTK_M(MONTH)):
-			/* Must be at second field of MM-DD-YY */
-			*tmask = DTK_M(DAY);
-			tm->tm_mday = val;
-			break;
-
 		case (DTK_M(YEAR) | DTK_M(MONTH) | DTK_M(DAY)):
 			/* we have all the date, so it must be a time field */
 			dterr = DecodeNumberField(flen, str, fmask,
@@ -2574,10 +2621,10 @@ DecodeNumber(int flen, char *str, int fmask,
 
 	/*
 	 * When processing a year field, mark it for adjustment if it's
-	 * exactly two digits.
+	 * only one or two digits.
 	 */
 	if (*tmask == DTK_M(YEAR))
-		*is2digits = (flen == 2);
+		*is2digits = (flen <= 2);
 
 	return 0;
 }

src/test/regress/sql/date.sql

@@ -28,6 +28,166 @@ SELECT f1 AS "Nine" FROM DATE_TBL WHERE f1 < '2000-01-01';
 SELECT f1 AS "Three" FROM DATE_TBL
   WHERE f1 BETWEEN '2000-01-01' AND '2001-01-01';
 
+--
+-- Check all the documented input formats
+--
+SET datestyle TO iso;  -- display results in ISO
+
+SET datestyle TO ymd;
+
+SELECT date 'January 8, 1999';
+SELECT date '1999-01-08';
+SELECT date '1999-01-18';
+SELECT date '1/8/1999';
+SELECT date '1/18/1999';
+SELECT date '18/1/1999';
+SELECT date '01/02/03';
+SELECT date '19990108';
+SELECT date '990108';
+SELECT date '1999.008';
+SELECT date 'J2451187';
+SELECT date 'January 8, 99 BC';
+
+SELECT date '99-Jan-08';
+SELECT date '1999-Jan-08';
+SELECT date '08-Jan-99';
+SELECT date '08-Jan-1999';
+SELECT date 'Jan-08-99';
+SELECT date 'Jan-08-1999';
+SELECT date '99-08-Jan';
+SELECT date '1999-08-Jan';
+
+SELECT date '99 Jan 08';
+SELECT date '1999 Jan 08';
+SELECT date '08 Jan 99';
+SELECT date '08 Jan 1999';
+SELECT date 'Jan 08 99';
+SELECT date 'Jan 08 1999';
+SELECT date '99 08 Jan';
+SELECT date '1999 08 Jan';
+
+SELECT date '99-01-08';
+SELECT date '1999-01-08';
+SELECT date '08-01-99';
+SELECT date '08-01-1999';
+SELECT date '01-08-99';
+SELECT date '01-08-1999';
+SELECT date '99-08-01';
+SELECT date '1999-08-01';
+
+SELECT date '99 01 08';
+SELECT date '1999 01 08';
+SELECT date '08 01 99';
+SELECT date '08 01 1999';
+SELECT date '01 08 99';
+SELECT date '01 08 1999';
+SELECT date '99 08 01';
+SELECT date '1999 08 01';
+
+SET datestyle TO dmy;
+
+SELECT date 'January 8, 1999';
+SELECT date '1999-01-08';
+SELECT date '1999-01-18';
+SELECT date '1/8/1999';
+SELECT date '1/18/1999';
+SELECT date '18/1/1999';
+SELECT date '01/02/03';
+SELECT date '19990108';
+SELECT date '990108';
+SELECT date '1999.008';
+SELECT date 'J2451187';
+SELECT date 'January 8, 99 BC';
+
+SELECT date '99-Jan-08';
+SELECT date '1999-Jan-08';
+SELECT date '08-Jan-99';
+SELECT date '08-Jan-1999';
+SELECT date 'Jan-08-99';
+SELECT date 'Jan-08-1999';
+SELECT date '99-08-Jan';
+SELECT date '1999-08-Jan';
+
+SELECT date '99 Jan 08';
+SELECT date '1999 Jan 08';
+SELECT date '08 Jan 99';
+SELECT date '08 Jan 1999';
+SELECT date 'Jan 08 99';
+SELECT date 'Jan 08 1999';
+SELECT date '99 08 Jan';
+SELECT date '1999 08 Jan';
+
+SELECT date '99-01-08';
+SELECT date '1999-01-08';
+SELECT date '08-01-99';
+SELECT date '08-01-1999';
+SELECT date '01-08-99';
+SELECT date '01-08-1999';
+SELECT date '99-08-01';
+SELECT date '1999-08-01';
+
+SELECT date '99 01 08';
+SELECT date '1999 01 08';
+SELECT date '08 01 99';
+SELECT date '08 01 1999';
+SELECT date '01 08 99';
+SELECT date '01 08 1999';
+SELECT date '99 08 01';
+SELECT date '1999 08 01';
+
+SET datestyle TO mdy;
+
+SELECT date 'January 8, 1999';
+SELECT date '1999-01-08';
+SELECT date '1999-01-18';
+SELECT date '1/8/1999';
+SELECT date '1/18/1999';
+SELECT date '18/1/1999';
+SELECT date '01/02/03';
+SELECT date '19990108';
+SELECT date '990108';
+SELECT date '1999.008';
+SELECT date 'J2451187';
+SELECT date 'January 8, 99 BC';
+
+SELECT date '99-Jan-08';
+SELECT date '1999-Jan-08';
+SELECT date '08-Jan-99';
+SELECT date '08-Jan-1999';
+SELECT date 'Jan-08-99';
+SELECT date 'Jan-08-1999';
+SELECT date '99-08-Jan';
+SELECT date '1999-08-Jan';
+
+SELECT date '99 Jan 08';
+SELECT date '1999 Jan 08';
+SELECT date '08 Jan 99';
+SELECT date '08 Jan 1999';
+SELECT date 'Jan 08 99';
+SELECT date 'Jan 08 1999';
+SELECT date '99 08 Jan';
+SELECT date '1999 08 Jan';
+
+SELECT date '99-01-08';
+SELECT date '1999-01-08';
+SELECT date '08-01-99';
+SELECT date '08-01-1999';
+SELECT date '01-08-99';
+SELECT date '01-08-1999';
+SELECT date '99-08-01';
+SELECT date '1999-08-01';
+
+SELECT date '99 01 08';
+SELECT date '1999 01 08';
+SELECT date '08 01 99';
+SELECT date '08 01 1999';
+SELECT date '01 08 99';
+SELECT date '01 08 1999';
+SELECT date '99 08 01';
+SELECT date '1999 08 01';
+
+RESET datestyle;
+
 --
 -- Simple math
 -- Leave most of it for the horology tests