Greatest value

Question

Hi,
One of my friend has given this problem to me.
I'm using 11g.
Two tables t1, t2. No relation exist between these two tables. Please find the table Scripts below.
-- Table t1
CREATE TABLE t1(col1 NUMBER, col2 NUMBER);
INSERT INTO t1 VALUES (1,2);
INSERT INTO t1 VALUES (NULL,10);
INSERT INTO t1 VALUES (3,4);
INSERT INTO t1 VALUES (89,NULL);
INSERT INTO t1 VALUES (5,6);
-- Table t2
CREATE TABLE t2(col1 NUMBER, col2 NUMBER);
INSERT INTO t2 VALUES (3,2);
INSERT INTO t2 VALUES (9,NULL);
INSERT INTO t2 VALUES (5,4);
INSERT INTO t2 VALUES (7,6);
INSERT INTO t2 VALUES (NULL,87);
COMMIT;
-- Table Data
SELECT *
FROM t1;
        COL1     COL2
     1     2
          10
     3     4
     89     
     5     6
SELECT *
FROM t2;
        COL1     COL2
     3     2
     9     
     5     4
     7     6
          87I need to retrieve greatest value from t1 and greatest value from t2 in two seperate columns.
Expected output:
        RES1          RES2
     2                3
     10              9
     4                5
     89              7
     6               87I was able to select RES1, RES2 individually using below code. But I dont know how to get the same using single SQl statement.
  SELECT  greatest(NVL(t1.col1,0),NVL(t1.col2,0)) res1
  FROM t1Please help me in getting required result from two tables using one SQl query.
Thanks,
Suri
Edited by: Suri on Jul 4, 2012 1:08 AM

Answer 1

Suri wrote:
Hi,
One of my friend has given this problem to me.
I'm using 11g.
Two tables t1, t2. No relation exist between these two tables. Please find the table Scripts below.
-- Table t1
CREATE TABLE t1(col1 NUMBER, col2 NUMBER);
INSERT INTO t1 VALUES (1,2);
INSERT INTO t1 VALUES (NULL,10);
INSERT INTO t1 VALUES (3,4);
INSERT INTO t1 VALUES (89,NULL);
INSERT INTO t1 VALUES (5,6);
-- Table t2
CREATE TABLE t2(col1 NUMBER, col2 NUMBER);
INSERT INTO t1 VALUES (3,2);
INSERT INTO t1 VALUES (9,NULL);
INSERT INTO t1 VALUES (5,4);
INSERT INTO t1 VALUES (7,6);
INSERT INTO t1 VALUES (NULL,87);
COMMIT;
-- Table Data
SELECT *
FROM t1;
     COL1     COL2
     1     2
          10
     3     4
     89     
     5     6
SELECT *
FROM t2;
     COL1     COL2
     3     2
     9     
     5     4
     7     6
          87I need to retrieve greatest value from t1 and greatest value from t2 in two seperate columns.
Expected output:
     RES1          RES2
     2                3
     10              9
     4                5
     89              7
     6               87I was able to select RES1, RES2 individually using below code. But I dont know how to get the same using single SQl statement.
SELECT  greatest(NVL(t1.col1,0),NVL(t1.col2,0)) res1
FROM t1Please help me in getting required result from two tables using one SQl query.
Thanks,
SuriDoesn't really make any sense seeing as how there is no way to join the results. You can make one up as i did below, but without some logical ordering attribute this goes back to making no sense.
ME_XE?with
  2     data1 as
  3  (
  4     select
  5        greatest(nvl(col1, 0), nvl(col2,0) )   as col1,
  6        row_number() over (order by 1)         as rn
  7     from t1
  8  ),
  9     data2 as
10  (
11     select
12        greatest(nvl(col1, 0), nvl(col2,0) )   as col1,
13        row_number() over (order by 1)         as rn
14     from t2
15  )
16  select d1.col1 as col1, d2.col1 as col2
17  from data1 d1 full outer join data2 d2
18  on (d1.rn = d2.rn);
              COL1               COL2
                 2                  3
                10                  9
                 4                  5
                89                  7
                 6                 87
5 rows selected.
Elapsed: 00:00:00.01
ME_XE?
ME_XE?Cheers,