Co0mparing two tables in mysql

I would like to compare two tables.  I need to compare multiple columns and count them.  I will need to compare upto 6 columns.  I found this query but have been unable to modify it for multiple columns.

 FROM tblB
 WHERE tblA.ID=tblB.ID
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nishant joshiTechnology Development ConsultantCommented:
means you want to need that record from A table which not in B table.
Then it is advisable to use outer join.

Outer Join tblB b
ON a.ID <> b.ID --AND more colums

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Agree with Nishant that an outer join is what is needed, except I usually do it this way:

select a.* from table1 a left outer join table2b
on (a.col1=b.col1 and a.col2=b.col2 and .... a.col6=b.col6)
where b.pimary_key_column is null;
ralphs1961Author Commented:
Thanks for the responses and I am going to try both.

It seems I made a mistake in my original question, what I am after is a count of rows that are the same.
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If what you need are the same, the query is different:

select count(a.primary_key_column) from table1 a join table2b
on (a.col1=b.col1 and a.col2=b.col2 and .... a.col6=b.col6);

a.primary_key_column can actually be any column, but I usually recommend the primary key, especially if it's innodb.

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ralphs1961Author Commented:
Thanks very much you both, I ran the query and it worked, It took 1/2 hour to complete, is there anyway to make it faster?  3,000 rows being compared to 14 million rows...  

I do have indexes setup but if you have any ideas please let me know.  If you think this last question should be a new question please let me know.
See if a concatenated index with all 6 columns will help.  Make sure you have them on both tables.  If it still doesn't help, please post output of EXPLAIN <query>
nishant joshiTechnology Development ConsultantCommented:
;with t1(cnt,id) as 
Outer Join tblB b
ON a.ID <> b.ID
group by a.ID
;with t2 as
SELECT cnt+1,id from t1
select cnt from t2

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use recurcive cte..
Nishant, does mysql already support that?  Last time I checked it still lagged behind the SQL standard and won't accept that yet.
ralphs1961Author Commented:
I would like to thank both of you for your help.  I am going to award johanntagle 400 points as he made the suggestion of concatenating the columns into a index.  Turned a half hour query into 5 seconds.  Thanks.  Both of the original queries worked and worked well with out the memory out error I was getting with the first query.
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