Minimum in and maximum out

Question

In a table i have the following columns , all were varchar2 column and sample data
workdate 10/22/2009
in1 7:48:28 AM
in2 12:46:01 PM
in3 null
out1 12:14:30 PM
out2 null
ou3 null
I need a query which retrieves minimum in and maximum out in DD-MON-YYYY HH24:MI:SS format.
if any of the in columns is null mimimum in should be null
if any of the out columns is null maximum out should be null
if minimum in is null,then its value should be equivalent to maximum out
if minimum out is null,then its value should be equivalent to minimum in
if workdate is null both minimum in and maximum out should be null.
Please help gurus...

Answer 1

Andreas Weiden wrote:
To make the LEAST and GREATEST-function work as desired, you may have to convert your varchar2 to date-vars using TO_DATEFirst of all, CASE for INs/OUTs is overcomplication. LEAST/GREATEST produces null if one of the items is null. However, since OP uses AM/PM notation you must+* (not may) convert to date. Otherwise:
SQL> WITH THETABLE AS (SELECT '10/22/2009' WORKDATE,
  2                           '7:48:28 AM' IN1,
  3                           '12:46:01 PM' IN2,
  4                           NULL IN3,
  5                          '12:14:30 PM' OUT1,
  6                           NULL          OUT2,
  7                           NULL          OUT3
  8                      FROM DUAL
  9                    UNION ALL
10                    SELECT '10/22/2009' WORKDATE,
11                           '7:48:28 AM' IN1,
12                           '12:46:01 PM' IN2,
13                           '12:46:02 PM' IN3,
14                           '12:14:30 PM' OUT1,
15                           NULL          OUT2,
16                           NULL          OUT3
17                      FROM DUAL
18                    UNION ALL
19                    SELECT '10/22/2009' WORKDATE,
20                           '7:48:28 AM' IN1,
21                           '2:46:01 PM' IN2,
22                           '2:46:02 PM' IN3,
23                           '9:14:30 AM' OUT1,
24                           '2:14:32 PM' OUT2,
25                           '3:14:34 PM' OUT3
26                      FROM DUAL
27                   )
28  SELECT  IN1,IN2,IN3,LEAST(IN1, IN2, IN3) LEAST_IN,
29          OUT1,OUT2,OUT3,GREATEST(OUT1, OUT2, OUT3) GREATEST_OUT
30    FROM THETABLE
31  /
IN1        IN2         IN3         LEAST_IN    OUT1        OUT2       OUT3       GREATEST_OU
7:48:28 AM 12:46:01 PM                         12:14:30 PM
7:48:28 AM 12:46:01 PM 12:46:02 PM 12:46:01 PM 12:14:30 PM
7:48:28 AM 2:46:01 PM  2:46:02 PM  2:46:01 PM  9:14:30 AM  2:14:32 PM 3:14:34 PM 9:14:30 AM
SQL> SY.