sql inner in appian

This code may help you 

a!localVariables(
local!list1: {"IT", "UK", "DZ", "USA"},
local!list2: {"DZ", "USA"},
local!list3: {"IT", "UK", "DZ"},

a!forEach(
items: local!list1,
expression: if(
and(contains(local!list2, fv!item), contains(local!list3, fv!item)),
fv!item,
{}
)
)
)

Do you need/want to solve this in the database?

[View:https://docs.appian.com/suite/help/24.1/fnc_set_intersection.html:320:50]

Do you want to do this for VIEW definition in database?

DO it in the database, merge the list in SAIL or use records.....

hi [mention:cdbe3381ad184204981f46f0aec54d80:e9ed411860ed4f2ba0265705b8793d05] instead of doing that in database it will be easy to do it in appian side using   intersection() this function will help you click on the link for more details of that function

By writing a query first get that three lists to Appian environment from Database then write this expression,

a!localVariables(
local!list1: {"IT", "UK", "DZ", "USA"},
local!list2: {"DZ", "USA"},
local!list3: {"IT", "UK", "DZ"},

intersection(local!list1,local!list2,local!list3)
)

list1: {"IT", "UK", "DZ", "USA"},
list2: {"DZ", "USA"},
list3: {"IT", "UK", "DZ"}

commonValues = intersection(list1, list2, list3);

---> commonValues' will contain {"DZ"} as it is the common element 

Hi [mention:cdbe3381ad184204981f46f0aec54d80:e9ed411860ed4f2ba0265705b8793d05] ,

The below code might help you

a!localVariables(
  local!list1: {"IT", "UK", "DZ", "USA"},
  local!list2: {"DZ", "USA"},
  local!list3: {"IT", "UK", "DZ"},
  local!intersection1:intersection(local!list1,local!list2),
  local!intersection2:intersection(local!intersection1,local!list3),
  local!intersection2
)