Oracle 21c

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CREATE TABLE Master_Tech_Email
(
  ID              NUMBER(10)  NOT NULL,
  SOMECOLUMN      VARCHAR2(40 BYTE),
  EMAIL           VARCHAR2(40 BYTE),
  TECHNOLOGY      NUMBER(10)
);
INSERT INTO Master_Tech_Email(ID, SOMECOLUMN, EMAIL, TECHNOLOGY)
VALUES(1000, 'a', 'aaa@aa.com', 1); 
1 rows affected

INSERT INTO Master_Tech_Email(ID, SOMECOLUMN, EMAIL, TECHNOLOGY)
VALUES(1001, 'b', 'bbb@bb.com', 2);
1 rows affected

INSERT INTO Master_Tech_Email(ID, SOMECOLUMN, EMAIL, TECHNOLOGY)
VALUES(1002, 'c', 'ccc@cc.com', 3);
1 rows affected

INSERT INTO Master_Tech_Email(ID, SOMECOLUMN, EMAIL, TECHNOLOGY)
VALUES(1003, 'd', 'ddd@dd.com', 4);
1 rows affected

CREATE TABLE MASTER_COURSE_OWNER
(
  ID              NUMBER(10)  NOT NULL,
  ANOTHERCOLUMN   VARCHAR2(40 BYTE),
  EMAIL           VARCHAR2(40 BYTE),
  TECHNOLOGY      NUMBER(10)
);
INSERT INTO MASTER_COURSE_OWNER(ID, ANOTHERCOLUMN, TECHNOLOGY)
VALUES(1,'z', 2);
1 rows affected

INSERT INTO MASTER_COURSE_OWNER(ID, ANOTHERCOLUMN, TECHNOLOGY)
VALUES(2,'y', 2)
1 rows affected

INSERT INTO MASTER_COURSE_OWNER(ID, ANOTHERCOLUMN, TECHNOLOGY)
VALUES(3,'x', 1)
1 rows affected

INSERT INTO MASTER_COURSE_OWNER(ID, ANOTHERCOLUMN, TECHNOLOGY)
VALUES(4,'x', 4)
1 rows affected

select * from MASTER_COURSE_OWNER


ID
ANOTHERCOLUMN
EMAIL
TECHNOLOGY


1
z
null
2

2
y
null
2

3
x
null
1

4
x
null
4


select * from Master_Tech_Email


ID
SOMECOLUMN
EMAIL
TECHNOLOGY


1000
a
aaa@aa.com
1

1001
b
bbb@bb.com
2

1002
c
ccc@cc.com
3

1003
d
ddd@dd.com
4


UPDATE MASTER_COURSE_OWNER SET EMail = (SELECT Email FROM Master_Tech_Email WHERE Technology = MASTER_COURSE_OWNER.Technology AND ROWNUM = 1)
4 rows affected

select * from MASTER_COURSE_OWNER


ID
ANOTHERCOLUMN
EMAIL
TECHNOLOGY


1
z
bbb@bb.com
2

2
y
bbb@bb.com
2

3
x
aaa@aa.com
1

4
x
ddd@dd.com
4

ID	SOMECOLUMN	EMAIL	TECHNOLOGY
1000	a	aaa@aa.com	1
1001	b	bbb@bb.com	2
1002	c	ccc@cc.com	3
1003	d	ddd@dd.com	4

ID	ANOTHERCOLUMN	EMAIL	TECHNOLOGY
1	z	null	2
2	y	null	2
3	x	null	1
4	x	null	4