SQLite script to MongoDB - sql

Question

I'm a newbie on MongoDB. And I need help. I have a small project with SQLite (7 tables and 1 view). And I need to make this project on MongoDB, I'm using Studio 3T, I'm already migrate SQLite tables to MongoDB collections, but now I need to make (VIEW/TEST) for test this project. Please help how to write this SQL script with MongoDB.
SQLITE:
MongoDB:
SQLIte script I want to make with MongoDB:
CREATE VIEW rezultatas AS
SELECT p.pavadinimas AS detales_pavadinimas,
SUM(d.pagamintas_kiekis) AS pagamintas_kiekis,
SUM(z.gamybos_islaidos) AS vidutine_kaina,
STRFTIME('%m', d.pagaminimo_data) AS menuo,
STRFTIME('%Y', d.pagaminimo_data) AS metai
FROM detales d,
zinynas z,
produktas p
WHERE (z.detale_id = p._id_) AND
(d.detale_id = z.detale_id) AND
(d.pagaminimo_data >= z.data_nuo) AND
NOT EXISTS (
SELECT *
FROM zinynas
WHERE (d.detale_id = detale_id) AND
(d.pagaminimo_data >= data_nuo) AND
(z.data_nuo < data_nuo)
)
GROUP BY p.pavadinimas,
STRFTIME('%m', d.pagaminimo_data),
STRFTIME('%Y', d.pagaminimo_data)

Answer 1

I had to guess some things due to the lack of schemes but the basic layout should work.
We're going to use $createView with these parameters as input:
db.createView('rezultatas', 'produktas', pipeline)
Meaning our pipeline creating the view starts with the produktas collection.
The pipeline to use:
[
{ // match the documents from the zinyas collection.
$lookup:
{
from: "zinynas",
let: { produktas_id: "$_id" }, // i'm guessing its _id
pipeline: [
{ $match:
{ $expr: { $eq: [ "$detale_id", "$$produktas_id" ] }}
},
],
as: "z"
}
},
{
$unwind: "$z"
},
{ // match the documents from the detales collection. only keep the one with maximum data_nuo value.
$lookup:
{
from: "detales",
let: { z_detale_id: "$z.detale_id", z_data_nuo: "$z.data_nuo" },
pipeline: [
{ $match:
{
$and: [
{ $expr: { $eq: [ "$detale_id", "$$z_detale_id" ] }},
{ $expr: { $gte: [ "$pagaminimo_data", "$$z_data_nuo"]}}
]
}
},
{
$sort: {
data_nuo: -1
}
},
{
$limit: 1
}
],
as: "d"
}
},
{
$unwind: "$d"
},
{ // end up saving the fields we want.
$group: {
_id: { pavadinimas : "$pavadinimas", month: {$month: "$d.pagaminimo_data"}, year: {$year: "$d.pagaminimo_data"}},
pagamintas_kiekis: {$sum: "$d.pagamintas_kiekis"},
vidutine_kaina: {$sum: "$z.gamybos_islaidos"},
month: {$first: {$month: "$d.pagaminimo_data"}},
year: {$first: {$year: "$d.pagaminimo_data"}},
detales_pavadinimas: {$first: "$pavadinimas"}
}
}
]