Question

I have a 2 tables – rout and loc.

Table Rout Columns:

Id (PK)
file_key
rout_no
....

This table has 800k records

Table Loc Columns

catalog_no(PK)
country_id    
...

This table has 700k records. So I want something like this (Intersection of between two tables)

SELECT rout.file_key,rout.rout_no,loc.country_id  
FROM ROUT_TBL rout, LOC_TBL loc 
WHERE rout.file_key != loc.catalog_no 

Can you tell me how?

Answer 1

I’m not sure that I understand what you’re asking. “Intersection” is a mathematical term that indicates that you want to determine which values exist in both tables. But the query you posted appears to be looking for the exact opposite– the set of rows in one table that don’t exist in the other.

If you really mean intersection

SELECT rout.file_key,
       rout.rout_no,
       loc.country_id
  FROM rout_tbl rout 
       JOIN loc_tbl loc ON (rout.file_key = loc.catalog_no)

If you want all the rows in ROUT that don’t exist in LOC

SELECT rout.file_key,
       rout.rout_no
  FROM rout_tbl rout
 WHERE NOT EXISTS( SELECT 1
                     FROM loc_tbl loc
                    WHERE loc.catalog_no = rout.file_key )

If you want the data from ROUT along with the data from LOC if it exists

SELECT rout.file_key,
       rout.rout_no,
       loc.country_id
  FROM rout_tbl rout 
       LEFT OUTER JOIN loc_tbl loc ON (rout.file_key = loc.catalog_no)