Convert a complex relational SQL query so that it runs in OrientDB - sql

Question

I am a newbie to OrientDB. I have a table structure as shown below. I have tried out a lot of queries but still cannot figure out how to implement the following SQL query in OrientDB. I need to join data from 4 different classes. Any help is greatly appreciated.
select Users.Name as uName,
Shops.Name as shopName,
ShopTotalPurchases.Total
from Users, Shops, Purchases,ShopTotalPurchases
where Users.Id=10
and Purchases.UserId=Users.Id
and Purchases.Date="date2"
and ShopTotalPurchases.Date="date2"
and ShopTotalPurchases.ShopId = Shops.Id
> reldb> SELECT * FROM Users;
+----+--------+-------+
| Id | Name | Phone |
+----+----------------+
| 10 | User 1 | 1111 |
+----+----------------+
| 20 | User 2 | 2222 |
+----+----------------+
> reldb> SELECT * FROM Shops;
+----+--------+-------+
| Id | Name | Phone |
+----+----------------+
| 30 | Shop 1 | 1111 |
+----+----------------+
| 40 | Shop 2 | 2222 |
+----+----------------+
> reldb> SELECT * FROM Purchases; [unique per combo of UserId, ShopId and Date]
+----+--------+--------+--------+------+-----------+
| Id | UserId | Item | ShopId | Date | ItemPrice |
+----+--------+-----------------+------+-----------+
| 0 | 10 | First | 30 |date1 | 100 |
+----+--------+--------+--------+------+-----------+
| 1 | 10 | Second | 30 |date2 | 200 |
+----+--------+--------+--------+------+-----------+
| 21 | 10 | Third | 40 |date3 | 300 |
+----+--------+--------+--------+------+-----------+
| 41 | 20 | Fourth | 40 |date4 | 400 |
+----+--------+--------+--------+------+-----------+
| 82 | 20 | Fift | 30 |date5 | 500 |
+----+--------+--------+--------+------+-----------+
> reldb> SELECT * FROM ShopTotalPurchases;
+----+--------+--------+------+
| Id | Total | ShopId | Date |
+----+--------+--------+------+
| 0 | 1000 | 30 |date1 |
+----+--------+--------+------+
| 1 | 2000 | 30 |date2 |
+----+--------+--------+------+
| 21 | 3000 | 40 |date2 |
+----+--------+--------+------+

Answer 1

you can use this query:
select $a.Name as uName, $b.Name as shopName, $c.Total as Total from Purchases
let $a = (select Name from User where Id = 10 and Id in $parent.current.UserId),
$b = (select Name from Shops where Id in $parent.current.ShopId),
$c = (select Total from ShopTotalPurchases where Date = 'date2' and ShopId in $parent.current.ShopId)
where Date = 'date2' unwind uName, shopName, Total
Console output:
----+------+-----+--------+------
# |#CLASS|uName|shopName|Total
----+------+-----+--------+------
0 |null |User1|Shop1 |2000.0
----+------+-----+--------+------