mysql - Exclude records from one table based on count in joined table -

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i have 2 tables: coupons , responses.

the coupons table includes fields such as:

  • vendorid [key]
  • couponid [key]
  • coupondescription

the responses table includes fields such as:

  • respondentid [key]
  • couponid [key]
  • (vendorid not repeated in table.)
  • accepted [true/false]
  • rejected [true/false]
  • rating [1 5]

when accepts coupon, rate in responses table. likewise, when rejects coupon, rejection appears in responses table.

when fetching list of available coupons coupons table, i'd exclude vendors received 2 or more rejections respondent. instance if respondentid 3 rejected 2 or more coupons vendor 47, coupons vendor 47 no longer shown respondentid 3.

two things make difficult sql novice myself.

  1. the first how write subquery counts rejections from particular vendor , by particular respondent.

  2. the second how join-back (so speak) responses table coupons table sub-query of responses table bases result on respondentid (which in responses table) , vendorid (which not in responses table , must determined based on couponid (which in both tables).

thanks assistance. it's appreciated.

could this:

   select * coupons       vendorid not in (         select c.vendorid            responses r join coupons c on r.couponid = c.couponid           r.respondentid = 3 , r.rejected = true           group c.vendorid           having sum(r.rejected) > 2      )

i've never used having without including value in select think work. also, not sure data type of rejected, sum() won't work.


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