[SQL left join] Multi-calls for the same data

[mansour_ib_sas]

Hello
I can't understand the idea that was developed in this SQL query.
Multi-calls were used for the Test1 table
Could you please help me with his understanding

Thank You

data test;
input name $  pur_id id;
cards;
A 1 2
B 2 3
C 3 4
D 4 5
E 5 6
F 6 7
G 7 8
H 8 9 
I 9 10
J 10 11
K 11 12
;run;

data test1;
input pur_id id;
cards;
1 2
2 3
3 4
4 5
5 6
6 7
7 8
8 9
9 10
10 11
;run;



proc sql;
create table test2 as select test.name, b.id as id_n1,c.id as id_n2,d.id as id_n3
from test left join test1 as b
on test.pur_id=test1.id
left join test1 as c
on b.pur_id=c.id
left join test1 as d
on c.pur_id=d.id
order by name
;quit;

[Kurt_Bremser]

The code follows a parent-child chain, max. 3 levels deep.

[mansour_ib_sas]

Thank you for your answer,

what is it for?

[Kurt_Bremser]

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@mansour_ib_sas wrote:

Thank you for your answer,

what is it for?

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Look at the documentation of the code.