SQL Case statement Help....

Question

Hi , I have to Compare two columns to see if they are matching or not....and give the count() of overrides if they are not matching/
I have got that with the below SQL:
Count of Overrides =
select count(Case when Col_1 != Col_2 then 1 else null end) Overrides
from table_1, table_2
where table_1.id = table_2.id
But now i have to look at two columns and get the count()
I have
col_1 and col_2 in table_1 and
col_3 and col_4 in table_2
(I have to compare col_1 with col_2 and...... col_3 with col_4 and if either of them is not matching.... count it as an override
Will the following SQL return correct values?
Count of Overrides =
Select
Count( Case when (col_1 ! = col_2) or (col_3 != col_4) then 1 else null end) Overrides
from table_1, table_2
where table_1.id = table_2.id
Thanks

Answer 1

"yes, it can be rewritten as a decode. but why bother?"
Well, although I do like Sy's code better, the decode version does naturally handle NULLs unlike the case.
SQL> WITH t AS (
  2     SELECT 1 col_1, 1 col_2, 2 col_3, 2 col_4 FROM dual UNION ALL
  3     SELECT 1, 1, 2, 3 FROM dual UNION ALL
  4     SELECT 1, 2, 3, 3 FROM dual UNION ALL
  5     SELECT null, 1, 2, 2 FROM dual UNION ALL
  6     SELECT 1, 1, 2, null FROM dual UNION ALL
  7     SELECT 1, 2, 3, 4 FROM dual)
  8  SELECT col_1, col_2, col_3, col_4,
  9         CASE WHEN (col_1 ! = col_2) or (col_3 != col_4) then 1 else null end Ocase,
10         DECODE(col_1, col_2, DECODE(col_3, col_4, NULL, 1), 1) odecode
11  FROM t;
     COL_1      COL_2      COL_3      COL_4      OCASE O
         1          1          2          2
         1          1          2          3          1 1
         1          2          3          3          1 1
                    1          2          2            1
         1          1          2                       1
         1          2          3          4          1 1John