Minus query / operator in Oracle

Question

I am working on a Oracle 11g db. I have Currency Table for which i have 182 records in the year 2013 and for the year 2014, i have 81 records. I have to get the difference 101 records from 2013. Missing / Difference records i have to insert into the year 2014.

I wonder whether my syntax is incorrect or any other method to generate the difference query.

SELECT 
a.CCYCD,
a.YEARNR
FROM CCYEXC a
WHERE  a.YEARNR = 2013

minus

SELECT 
a.CCYCD,
a.YEARNR
FROM CCYEXC a
WHERE  a.YEARNR = 2014;

Answer 1

SELECT CCYCD
     , YEARNR
  FROM CCYEXC
 WHERE YEAR_NR = 2014
   AND CCYCD,YEARNR NOT IN 
           (
      SELECT CCYCD
           , YEARNR
        FROM CCYEXC
       WHERE YEAR_NR = 2013 
           );

Answer 2

Your usage of MINUS is correct. When you want SET difference, MINUS is correct way to go. Note that some other databases use EXCEPT keyword for this operation.

Following set operations are available.

• UNION (ALL)
• INTERSECT
• MINUS/EXCEPT

Answer 3

You only need to have the CCYCD column in the SELECT list in the MINUS query. Now, to insert this result into the table for year 2014, just write an i sert statement like this,

INSERT INTO ccyexc SELECT ccycd, 2014 as "yearnr" FROM( <your MINUS query> );

Answer 4

EXISTS usually faster:

SELECT a.CCYCD, a.YEARNR
FROM CCYEXC a
WHERE  a.YEARNR = 2013
  and not exists (select 1 from CCYEXC b where b.YEARNR = 2014 and b.CCYCD = a.CCYCD);

Another option:

SELECT a.CCYCD, a.YEARNR
FROM CCYEXC a
WHERE  a.YEARNR = 2013
  and a.CCYCD not in (select distinct CCYCD from CCYEXC b where b.YEARNR = 2014);  

Also you can use LEFT JOIN

MINUS doesn't work because both sets (subqueries) have different YEARNR (they don't intersect)

Answer 5

A shorter way to write this is to use aggregation:

SELECT c.CCYCD,
FROM CCYEXC c
GROUP BY c.CCYCD
HAVING SUM(CASE WHEN c.YEARNR = 2013 THEN 1 ELSE 0 END) > 0 AND
       SUM(CASE WHEN c.YEARNR = 2014 THEN 1 ELSE 0 END) = 0;

Or, as others have suggested, a NOT EXISTS or NOT IN clause.