How do I make an algorithm for joining in SQL

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SQL

SQL-Server

T-SQL

C#6.0

Hello Every One, I'm working on a project (C# and SQL Server) where the user can select some fields for a select output from multiple tables in the database.
I'm in front of the problem: how can I manage the joining problem between tables whom are not directly connected.
For Example Between: [Compte] and [Encaissement].
You can see Image Dor the Schema: Schema of DB

What I have tried:

I tried a Mapping table to store every relationship between two table, Image Of The Table.

And I maked Also a stored procedure that take 2 argument @table1 and @table2 for searching the relationship in the mapping table, it return one row if the 2 tables are directly connected or one rows if there is a link table between them.
Picture Of The Stored Procedure.
To Here all it's good and works fine, but I need a generic algorithm that can work with n ink between the tables in select query.

Thank You, I'll be very grateful for your help.

That Is The script:
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use master;
go
set dateformat DMY
go
if exists (select * from
		   sys.databases where name='INTERMEDIAIRE')
		   drop database INTERMEDIAIRE;
go
create database INTERMEDIAIRE;
go
use INTERMEDIAIRE;
go
create table [Authentication](
	id int identity(1,1)
	constraint pk_auth primary key,
	username varchar(10) not null unique,
	mdp varchar(20) not null
);
go
create table Conditions(evenement varchar(255) not null,
						systeme varchar(255) not null,
						tempTable varchar(max) not null,
						constraint pk_events primary key(evenement,systeme));
go
create table Structures(id int identity(1,1)
					   constraint pk_conditions primary key,
					   champs varchar(max) not null,
					   [type] varchar(max) not null,
					   taille int not null,
					   nomFonctionnel varchar(max),
					   ref_event varchar(max),
					   sysTable varchar(max) not null);
go
create table Mapping(table1 varchar(255) not null,
					 table2 varchar(255) not null,
					 key1 varchar(max) not null,
					 key2 varchar(max) not null,
					 constraint pk_map primary key(table1,table2));
go
--Inserttion Of Records
insert into [Authentication] values('user1','pass1');
insert into [Authentication] values('user2','pass2');
go
insert into Conditions values('Facturation','Vectis','TmpFactVectis');
go
--the table [Structures] Will be filled from an Excel file in My Application(Does Not Matter for now)
--There are the datas If you need them
/*
id	champs				type	taille	nomFonctionnel		ref_event	sysTable
==  ================    ======= ======  ================    =========== =============
1	ref_facture			int		5		IdFacture			Facturation	Facture
2	num_contrat_fact	int		6		Ncontrat			Facturation	Facture
3	dateFacture			date	10		DateFact			Facturation	Facture
4	id_client			int		6		Id_Acheteur			Facturation	Client
5	num_contrat_cli		int		6		Contrat_Client		Facturation	Client
6	nom					varchar	255		Nom_Client			Facturation	Client
7	type				varchar	15		Type_Client			Facturation	Client
8	qte					int		3		Qte					Facturation	DetailFacture
9	prix				decimal	15		Prix				Facturation	DetailFacture
10	tax					decimal	3		TVA					Facturation	DetailFacture
11	montant_paye		decimal	15		MtEncaissement		Facturation	Encaissement
12	date_operation		date	10		DtEncaissement		Facturation	Encaissement
13	type_operation		varchar	20		TypeEncaissement	Facturation	Encaissement
14	date_paiment		date	10		DtPaiment			Facturation	Paiment
15	montant_total		decimal	15		MtTTC				Facturation	Paiment
*/
go
insert into Mapping values('Client','Facture','id_client','client');
insert into Mapping values('DetailFacture','Facture','facture','ref_facture');
insert into Mapping values('Encaissement','Facture','facture','ref_facture');
insert into Mapping values('Paiment','Facture','facture','ref_facture');
insert into Mapping values('Compte','Client','id_compte','compte');
insert into Mapping values('Auth','Compte','id_auth','auth');
go
--Create the stored procedure responsible of the mapping
create procedure sp_GetMapping
@t1 varchar(255),@t2 varchar(255)
as
BEGIN
	--the cases when (table1=@t1 & table2=@tb) OR (table1=@t2 & table2=@t1)
	if exists(select * from Mapping where (table1=@t1 and table2=@t2))
		select * from Mapping where (table1=@t1 and table2=@t2)
	else if exists(select * from Mapping where (table1=@t2 and table2=@t1))
		select * from Mapping where (table1=@t2 and table2=@t1)
	--End of the two cases
	else
		--the query responsible to find the link table between two tables (@t1 and @t2)
		select * from Mapping
		where ((table1=@t1 and table2=(select table2 from Mapping where table1=@t2)) or
			   (table1=@t2 and table2=(select table2 from Mapping where table1=@t1))) 
			  or
			  ((table2=@t1 and table1=(select table1 from Mapping where table2=@t2))or
			   (table2=@t2 and table1=(select table1 from Mapping where table2=@t1)))
			  or
			  ((table1=@t1 and table2=(select table1 from Mapping where table2=@t2))or
			   (table2=@t2 and table1=(select table2 from Mapping where table1=@t1)))
			  or
			  ((table1=@t2 and table2=(select table1 from Mapping where table2=@t1))or
			   (table2=@t1 and table1=(select table2 from Mapping where table1=@t2)))
END
go
select * from Authentication;
select * from Conditions;
select * from Structures;
select * from Mapping;
go
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