db_finalize(&q);
    rc = 0;
  }else{
    rc = 0;
  }
  return rc;
}

/*
** Return TRUE if the string begins with an ISO8601 date: YYYY-MM-DD.
*/
static int is_date(const char *z){
  if( !isdigit(z[0]) ) return 0;
  if( !isdigit(z[1]) ) return 0;
  if( !isdigit(z[2]) ) return 0;
  if( !isdigit(z[3]) ) return 0;
  if( z[4]!='-') return 0;
  if( !isdigit(z[5]) ) return 0;
  if( !isdigit(z[6]) ) return 0;
  if( z[7]!='-') return 0;
  if( !isdigit(z[8]) ) return 0;
  if( !isdigit(z[9]) ) return 0;
  return 1;
}

/*
** Convert a symbolic tag name into the UUID of a check-in that contains
** that tag.  If the tag appears on multiple check-ins, return the UUID
** of the most recent check-in with the tag.
**
** If the input string is of the form:
**
**      tag:date
**
** Then return the UUID of the oldest check-in with that tag that is
** not older than 'date'.
**
** Memory to hold the returned string comes from malloc() and needs to
** be freed by the caller.
*/
char *tag_to_uuid(const char *zTag){
  char *zUuid = 
    db_text(0,
       "SELECT blob.uuid"
       "  FROM tag, tagxref, event, blob"
       " WHERE tag.tagname='sym-'||%Q "
       "   AND tagxref.tagid=tag.tagid AND tagxref.tagtype>0 "
       "   AND event.objid=tagxref.rid "
       "   AND blob.rid=event.objid "
       " ORDER BY event.mtime DESC ",
       zTag
    );
  if( zUuid==0 ){
    int nTag = strlen(zTag);
    int i;
    for(i=0; i<nTag-10; i++){
      if( zTag[i]==':' && is_date(&zTag[i+1]) ){
        char *zDate = mprintf("%s", &zTag[i+1]);
        char *zTagBase = mprintf("%.*s", i, zTag);
        int nDate = strlen(zDate);
        int useUtc = 0;
        if( sqlite3_strnicmp(&zDate[nDate-3],"utc",3)==0 ){
          nDate -= 3;
          zDate[nDate] = 0;
          useUtc = 1;
        }
        zUuid = db_text(0,
          "SELECT blob.uuid"
          "  FROM tag, tagxref, event, blob"
          " WHERE tag.tagname='sym-'||%Q "
          "   AND tagxref.tagid=tag.tagid AND tagxref.tagtype>0 "
          "   AND event.objid=tagxref.rid "
          "   AND blob.rid=event.objid "
          "   AND event.mtime<=julianday(%Q %s)"
          " ORDER BY event.mtime DESC ",
          zTagBase, zDate, (useUtc ? "" : ",'utc'")
        );
        break;
      }
    }
  }
  return zUuid;
}

/*
** Convert a date/time string into a UUID.
**
** Input forms accepted:

  }else if( memcmp(zDate, "local:", 6)==0 ){
    zDate += 6;
  }else if( memcmp(zDate, "utc:", 4)==0 ){
    zDate += 4;
    useUtc = 1;
  }
  n = strlen(zDate);
  if( n<10 || !is_date(zDate) ) return 0;
  if( n>4 && sqlite3_strnicmp(&zDate[n-3], "utc", 3)==0 ){
    zCopy = mprintf("%s", zDate);
    zCopy[n-3] = 0;
    zDate = zCopy;
    n -= 3;
    useUtc = 1;
  }