Question

I have two tables
table-a

id   name
100    asd
101    ass
102    gdd
103    hgf
104    cvd
105    erf

table-b

id     filter
100     red
101     blue
100     green
100     yellow
102     black
102     red
103     dark

Table-a is the master table and that have all the id’s.but Table two is the one which has ‘filter’ data.
from these two table I want to find out all those ‘id’s which does not have minimum 2 filters.
note that table-b does not have all the itemnumbers in table-a, and i want all that itemnumber irrespective of if that is in table-a or table-b.I have tried inner joining these two tables and getting data out but nothing worked.

Answer 1

Select A.ID, A.Name, count(*)
from tableA A
LEFT JOIN tableB B on A.ID = B.ID
Group By A.ID, A.name
having count(*) <= 1

• LEFT JOIN gives all records from A and only those in B which match.
• The group by ID and name let us count the number of filters found in
  each

• The having says give me any items with a count less than or
  equal to 1. (or less than the minimum 2)

  Thus results would be.

  101 ass 1
  103 hgf 1
  104 cvd 0 
  105 erf 0