How select from two different tables with multiple foreign keys - sql

Question

First explain what I need using an image:
Second creation tables:
CREATE SEQUENCE SEQ_tab7 MINVALUE 1 MAXVALUE 9999999999999999999999999999 INCREMENT BY 1 START WITH 2206 NOCACHE ORDER NOCYCLE NOKEEP NOSCALE GLOBAL ;
CREATE SEQUENCE SEQ_tab8 MINVALUE 1 MAXVALUE 9999999999999999999999999999 INCREMENT BY 1 START WITH 2206 NOCACHE ORDER NOCYCLE NOKEEP NOSCALE GLOBAL ;
CREATE TABLE TABLE_7
(
ID NUMBER(19,0) DEFAULT SEQ_tab7.nextval NOT NULL
,DESCRIPTION VARCHAR2(256) NOT NULL
,CONSTRAINT TAB_7_PK PRIMARY KEY (ID) ENABLE
);
CREATE TABLE TABLE_8
(
ID NUMBER(19,0) DEFAULT SEQ_tab8.nextval NOT NULL
,FIELD_1 NUMBER(19,0) NOT NULL
,FIELD_2 NUMBER(19,0) NOT NULL
,FIELD_3 NUMBER(19,0) NOT NULL
,FIELD_4 VARCHAR2(256)
,CONSTRAINT TAB_8_PK PRIMARY KEY (ID) ENABLE
,CONSTRAINT tab_8_FIELD_1_FK FOREIGN KEY (FIELD_1) REFERENCES TABLE_7(ID)
,CONSTRAINT tab_8_FIELD_2_FK FOREIGN KEY (FIELD_2) REFERENCES TABLE_7(ID)
,CONSTRAINT tab_8_FIELD_3_FK FOREIGN KEY (FIELD_3) REFERENCES TABLE_7(ID)
);
Third - inserts:
Insert into TABLE_7 (ID,DESCRIPTION) values ('1','desc_1');
Insert into TABLE_7 (ID,DESCRIPTION) values ('2','desc_2');
Insert into TABLE_7 (ID,DESCRIPTION) values ('3','desc_3');
Insert into TABLE_8 (ID,FIELD_1,FIELD_2,FIELD_3,FIELD_4) values ('23','1','2','1','lorem_1');
Insert into TABLE_8 (ID,FIELD_1,FIELD_2,FIELD_3,FIELD_4) values ('43','1','3','3','lorem_2');
Insert into TABLE_8 (ID,FIELD_1,FIELD_2,FIELD_3,FIELD_4) values ('54','3','3','3','lorem_3');
How could I get the desired results?
Best regards

Answer 1

Use multiple joins
Try this:
SELECT Base.ID, FirstJoin.Desc, SecondJoin.Desc, ThirdJoin.Desc, Base.field_4
FROM table_2 Base
JOIN table_1 FirstJoin ON FirstJoin.ID = Base.Field_1
JOIN table_1 SecondJoin ON SecondJoin.ID = Base.Field_2
JOIN table_1 ThirdJoin ON ThirdJoin.ID = Base.Field_3

Answer 2

Here is an example which use subqueries for each field_? it will search in table_1 for the description and use it as an attribute. I added alias for the field to make the output more clear.
SELECT
table_2.id,
(SELECT table_1.desc FROM table_1 WHERE table_1.id=table_2.field_1) as "FIELD_1",
(SELECT table_1.desc FROM table_1 WHERE table_1.id=table_2.field_2) as "FIELD_2",
(SELECT table_1.desc FROM table_1 WHERE table_1.id=table_2.field_3) as "FIELD_3",
table_2.field_4
FROM table_2;
For example the first row of table_2 is (id=23, field_1=1, field_2=2, field_3=1, field_4="lorem_1") The second attribute after performing the suggested query will be the result of the query SELECT table_1.desc FROM table_1 WHERE table_1.id=table_2.field_1 which is "desc_1" and the same process for the field_2 and field_3
in that case the result for the first row will be:
ID FIELD_1 FIELD_2 FIELD_3 FIELD_4
23 desc_1 desc_2 desc_1 lorem_1