Avoid multiple left joins in MSSQL - sql-server

Question

I have the following database structure:
Users
----------------------
| User_ID | Username |
|--------------------|
| 14590 | Sam |
| 14591 | Michael |
| 14592 | Albert |
----------------------
Addresses
----------------------------------------------
| Adr_ID | City | Street |
|--------------------------------------------|
| 62 | New York | Perfect Street 1 |
| 63 | New York | Another Street 12 |
| 64 | Prague | Zlata Ulicka 52 |
| 65 | Berlin | Alexanderplatz 36 |
| 66 | Berlin | Am Bahnhof 49 |
| 67 | Warsaw | Poniatowskiego 74 |
| 68 | Paris | Rue Des Barres 33 |
| 69 | Paris | Rue De L’abreuvoir 63 |
| 70 | Lisbon | Rua Augusta |
----------------------------------------------
Addresses_Link
------------------------------------------------------------
| Link_ID | Adr_ID | User_ID | Main_Address | Address_Type |
|----------------------------------------------------------|
| 570 | 62 | 14590 | 1 | 1 |
| 571 | 63 | 14590 | 1 | 2 |
| 572 | 64 | 14590 | 0 | 3 |
| 573 | 65 | 14591 | 1 | 1 |
| 574 | 66 | 14591 | 1 | 2 |
| 575 | 67 | 14591 | 0 | 3 |
| 576 | 68 | 14592 | 1 | 1 |
| 577 | 69 | 14592 | 1 | 2 |
| 578 | 70 | 14592 | 0 | 3 |
------------------------------------------------------------
The result I want to get:
-----------------------------------------------------------------------------------------------------
| User_ID | Username | Adr_Private_City | Adr_Private_Street | Adr_Job_City | Adr_Job_Street |
|---------------------------------------------------------------------------------------------------|
| 14590 | Sam | New York | Perfect Street 1 | New York | Another Street 12 |
| 14591 | Michael | Berlin | Alexanderplatz 36 | Berlin | Am Bahnhof 49 |
| 14592 | Albert | Paris | Rue Des Barres 33 | Paris | Rue De L’abreuvoir 63 |
-----------------------------------------------------------------------------------------------------
Columns:
Adr_Private_City / Adr_Private_Street - when Main_Address = 1 and Address_Type = 1
Adr_Job_City / Adr_Job_Street - when Main_Address = 1 and Address_Type = 2
I created an SQL query like this:
SELECT
u.User_ID,
u.Username,
a1.City AS Adr_Private_City,
a1.Street AS Adr_Private_Street,
a2.City AS Adr_Job_City,
a2.Street AS Adr_Job_Street
FROM Users u
LEFT JOIN Addresses_Link al1 ON al1.User_ID = u.User_ID
LEFT JOIN Addresses_Link al2 ON al2.User_ID = u.User_ID
LEFT JOIN Addresses a1 ON a1.Adr_ID = al1.Adr_ID
LEFT JOIN Addresses a2 ON a2.Adr_ID = al2.Adr_ID
WHERE
al1.Main_Address = 1 AND al1.Address_Type = 1 AND
al2.Main_Address = 1 AND al2.Address_Type = 2
Is it possible to avoid multiple left joins and make the query not too slow?

Answer 1

You can achieve what you want with below
Your original query
FROM Users u
LEFT JOIN Addresses_Link al1 ON al1.User_ID = u.User_ID
....
WHERE al1.Main_Address = 1
effectively is an INNER JOIN, when you have the condition al1.Main_Address = 1 in the WHERE clause
Since you used LEFT JOIN, I have turn it into a true LEFT JOIN query. For Addresses_Link and Addresses, since you join it on Adr_ID, I use INNER JOIN
SELECT *
FROM Users u
LEFT JOIN
(
SELECT al.User_ID,
MAX(CASE WHEN al.Address_Type = 1 THEN a.City END) AS Adr_Private_City,
MAX(CASE WHEN al.Address_Type = 1 THEN a.Street END) AS Adr_Private_Street,
MAX(CASE WHEN al.Address_Type = 2 THEN a.City END) AS Adr_Job_City,
MAX(CASE WHEN al.Address_Type = 2 THEN a.Street END) AS Adr_Job_Street,
FROM Addresses_Link al
INNER JOIN Addresses a ON a.Adr_ID = al.Adr_ID
WHERE al.Main_Address = 1
AND al.Address_Type IN (1, 2)
GROUP BY al.User_ID
) a ON a.User_ID = u.User_ID