MySQL 8.0

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CREATE TABLE Table1 (id INT,status VARCHAR(50));

INSERT INTO Table1 (id,status) 
VALUES
(1,'active'),
(2,'active'),
(3,'away');

select * from Table1


id
status


1
active

2
active

3
away


-- Tab2 simulates the view.

CREATE TABLE Table2 (id INT,session INT, rand1 VARCHAR(50));

INSERT INTO Table2 (id,session,rand1) 
VALUES
(1,1,'BRK'),
(1,2,'GOOG'),
(2,1,'HOG'),
(2,2,'XOM'),
(3,1,'INTC'),
(3,2,'MSFT');

select * from Table2


id
session
rand1


1
1
BRK

1
2
GOOG

2
1
HOG

2
2
XOM

3
1
INTC

3
2
MSFT


CREATE TABLE Table3 (id INT,session VARCHAR(50),rand1 VARCHAR(50));

INSERT INTO Table3 (id,session,rand1) 
VALUES
(1,1,NULL),
(1,2,NULL),
(2,1,NULL),
(2,2,NULL),
(3,1,NULL),
(3,2,NULL);

select * from Table3


id
session
rand1


1
1
null

1
2
null

2
1
null

2
2
null

3
1
null

3
2
null


CREATE TRIGGER trigger1
AFTER UPDATE
ON Table1
FOR EACH ROW
BEGIN

IF (NEW.status <> OLD.status)
 THEN update Table3
    SET rand1 = ( SELECT rand1
    FROM Table2
where (Table3.id = NEW.id /*and Table2.session = Table3.session*/)
        limit 1);
    end if;

end;
UPDATE Table1
Set status = 'away'
Where id = 1;

UPDATE Table1
Set status = 'away'
Where id = 2;


select * from Table3


id
session
rand1


1
1
null

1
2
null

2
1
BRK

2
2
BRK

3
1
null

3
2
null


UPDATE Table2
Set rand1 = 'Test'
Where id = 1 and session = 1;

UPDATE Table1
Set status = 'Active'
Where id = 1;

select * from Table3


id
session
rand1


1
1
Test

1
2
Test

2
1
null

2
2
null

3
1
null

3
2
null
id	session	rand1
1	1	null
1	2	null
2	1	null
2	2	null
3	1	null
3	2	null