[SOLVED] mysql joins query.

[nishantcm]

Hi.

 

I am using php with mysql. I have a table cardtags. There are two columns- cardtagid and tagid.

 

Plz see the attached image. The page for tag A will contain 1,2,7,8,10,11

 

I want to display links to tags B and C in page for tag A. Here link for tag D will not be displayed because none of the items are overlapping.

Similarly, page for tag C will contain links to tags A, B, and D. So I want a query that will give me A,B,D as result when I have tag C as a parameter.

 

I think this can be done with joins. Can anyone help me with this?

 

Thanks.

Nishant

 

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[ann]

I may not fully understand your problem from the description you gave but maybe a sub query is what you're after?

 

select cardtagid from cardtags where tagid='C';

 

Should give you a result of 5,6,7,8,9,13. So a query for all tagid's that have a cardtag in the list 5,6,7,8,9,13 would be something like...

 

Select distinct(tagid) from cardtags where cardtagid in (select cardtagid from cardtags where tagid='C');

 

which should give you A, B, C, D. Then to get rid of the tagid you used as a parameter, in this case C, add and tagid!='C' to the query...

 

Select distinct(tagid) from cardtags where cardtagid in (select cardtagid from cardtags where tagid='C') add and tagid!='C';

 

Hope that helps.

 

[nishantcm]

A frnd helped me with this. Heres the query

 

SELECT DISTINCT t1.set

FROM table t

LEFT JOIN table t1 ON t.item = t1.item

WHERE t.set = 'A' AND t1.set <> 'A'