sql - How do you explicitly show rows which have count(*) equal to 0 -

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the query i'm running in db2 

select  yrb_customer.name,          yrb_customer.city,          case count(*) when 0 0 else count(*) end #uniclubs   yrb_member, yrb_customer  yrb_member.cid = yrb_customer.cid , yrb_member.club '%club%'  group yrb_customer.name, yrb_customer.city  order count(*)

shows me people part of clubs has word 'club' in it, , shows how many such clubs part of (#uniclubs) along name , city. students not part of such club, still them show have 0 instead of them being hidden what's happening right now. cannot functionality count(*). can shed light? can explain further if above not clear enough.

you're going want left join:

select yrb_customer.name, yrb_customer.city,        count(yrb_member.club) clubcount yrb_customer left join yrb_member        on yrb_member.cid = yrb_customer.cid           , yrb_member.club '%club% group yrb_customer.name, yrb_customer.city order clubcount

also, if tuple (yrb_customer.name, yrb_customer.city) unique (or supposed - counting students same name same person?), might better performance out of following:

select yrb_customer.name, yrb_customer.city,        coalesce(club.count, 0) yrb_customer left join (select cid, count(*) count            yrb_member            club '%club%            group cid) club        on club.cid = yrb_customer.cid order club.count

the reason original results being hidden because in original query, have implicit inner join, of course requires matching rows. implicit-join syntax (comma-separated from clause) great inner (regular) joins, terrible left-joins, needed. use of implicit-join syntax (and types of related filtering in where clause) considered deprecated.


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