Revert recent change of to_char('HH12') handling for intervals; instead

improve documentation, and add C comment.

diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 52049e7a7387373f4642842d69e6a02eb2f16a09..689cd34e93be14ac47a46a784eb3397516566b8d 100644 (file)
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -1,4 +1,4 @@
-
+
 
  
   Functions and Operators
@@ -5317,8 +5317,9 @@ SELECT SUBSTRING('XY1234Z', 'Y*?([0-9]{1,3})');
      
       
         to_char(interval) formats HH and
-        HH12 as hours in a single day, while HH24
-        can output hours exceeding a single day, e.g., >24.
+        HH12 as shown on a 12-hour clock, i.e. zero hours
+        and 36 hours output as 12, while HH24
+        outputs the full hour value, which can exceed 23 for intervals.
       
      
 

diff --git a/src/backend/utils/adt/formatting.c b/src/backend/utils/adt/formatting.c
index a41f6f1496b65dd3debcebcb1338683ede761d6b..af764e8edb0c555e09410e86ec8c0cf27773eb77 100644 (file)
--- a/src/backend/utils/adt/formatting.c
+++ b/src/backend/utils/adt/formatting.c
@@ -1,7 +1,7 @@
 /* -----------------------------------------------------------------------
  * formatting.c
  *
- * $PostgreSQL: pgsql/src/backend/utils/adt/formatting.c,v 1.165 2010/02/23 06:29:01 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/utils/adt/formatting.c,v 1.166 2010/02/23 16:14:26 momjian Exp $
  *
  *
  *  Portions Copyright (c) 1999-2010, PostgreSQL Global Development Group
@@ -2088,10 +2088,10 @@ DCH_to_char(FormatNode *node, bool is_interval, TmToChar *in, char *out)
                break;
            case DCH_HH:
            case DCH_HH12:
+               /* display time as shown on a 12-hour clock, even for intervals */
                sprintf(s, "%0*d", S_FM(n->suffix) ? 0 : 2,
-                       is_interval ? tm->tm_hour :
-                       tm->tm_hour % (HOURS_PER_DAY / 2) == 0 ?
-                       12 : tm->tm_hour % (HOURS_PER_DAY / 2));
+                       tm->tm_hour % (HOURS_PER_DAY / 2) == 0 ? 12 :
+                       tm->tm_hour % (HOURS_PER_DAY / 2));
                if (S_THth(n->suffix))
                    str_numth(s, s, S_TH_TYPE(n->suffix));
                s += strlen(s);