Unexpected Result Sets by Changing MAX to MIN

Question

I was expecting the identical result sets from the following two SQL statements:
SELECT HIST.LDR_SYSTEM_ID "MISSING SYSTEM PK"
FROM GM_SYSTEM_HIST HIST
WHERE HIST.SYSTEM_HIST_ID = (SELECT MAX (DUPL.SYSTEM_HIST_ID) /* SYSTEM_HIST_ID is the PK for GM_SYSTEM_HIST */
FROM GM_SYSTEM_HIST DUPL
WHERE HIST.LDR_SYSTEM_ID = DUPL.LDR_SYSTEM_ID)
AND HIST.LDR_SYSTEM_ID NOT IN (SELECT SYSTEM_ID FROM GM_SYSTEM) /* SYSTEM_ID is the PK for GM_SYSTEM */
AND HIST.SYSTEM_HIST_ID IN
(SELECT SYSTEM_HIST_ID FROM GM_INTGRTY_INVN
UNION
SELECT SYSTEM_HIST_ID FROM GM_INTGRTY_PROXIMITY);
SELECT HIST.LDR_SYSTEM_ID "MISSING SYSTEM PK"
FROM GM_SYSTEM_HIST HIST
WHERE HIST.SYSTEM_HIST_ID = (SELECT MIN (DUPL.SYSTEM_HIST_ID) /* SYSTEM_HIST_ID is the PK for GM_SYSTEM_HIST */
FROM GM_SYSTEM_HIST DUPL
WHERE HIST.LDR_SYSTEM_ID = DUPL.LDR_SYSTEM_ID)
AND HIST.LDR_SYSTEM_ID NOT IN (SELECT SYSTEM_ID FROM GM_SYSTEM) /* SYSTEM_ID is the PK for GM_SYSTEM */
AND HIST.SYSTEM_HIST_ID IN
(SELECT SYSTEM_HIST_ID FROM GM_INTGRTY_INVN
UNION
SELECT SYSTEM_HIST_ID FROM GM_INTGRTY_PROXIMITY);
MISSING SYSTEM PK
411539
610343
311152
311155
431231
631785
6 rows selected.
MISSING SYSTEM PK
332000
612339
2 rows selected.
Why would the result sets change from MAX to MIN?

Answer 1

Bob from Austin wrote:
I was expecting the identical result sets from the following two SQL statements:And why would they be the same? Assume table GM_SYSTEM_HIST has:
SYSTEM_HIST_ID LDR_SYSTEM_ID
1              10
2              10
3              10Now, even though resgrless if you use MAX or MIN you will get back LDR_SYSTEM_ID = 10, using MAX will return row
3              10while using MIN will return row:
1              10And it could be row
3              10satisfies other where clause conditions:
    AND HIST.LDR_SYSTEM_ID NOT IN (SELECT SYSTEM_ID FROM GM_SYSTEM) /* SYSTEM_ID is the PK for GM_SYSTEM */
    AND HIST.SYSTEM_HIST_ID IN (
                                 SELECT SYSTEM_HIST_ID FROM GM_INTGRTY_INVN
                                UNION
                                 SELECT SYSTEM_HIST_ID FROM GM_INTGRTY_PROXIMITY
                               );while row
1              10does not. Or vice versa.
SY.
Edited by: Solomon Yakobson on Dec 16, 2009 2:49 PM