MariaDB 10.2

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CREATE TABLE A (col1 varchar(10), col2 varchar(10), col3 varchar(10));
CREATE TABLE B (col1 varchar(10), col2 varchar(10), col3 varchar(10));
INSERT INTO A (col3) VALUES ('1');
INSERT INTO B (col3) VALUES ('1'), ('2'), ('3');
SELECT * FROM A;


col1
col2
col3


null
null
1


SELECT * FROM B;


col1
col2
col3


null
null
1

null
null
2

null
null
3


UPDATE
  A,
  B
    INNER JOIN
    (
      SELECT 'a' AS col1, 'x' AS col2, '1' AS col3
      UNION ALL
      SELECT 'b', 'y', '2'
      UNION ALL
      SELECT 'c', 'z', '3'
    ) AS fltr ON B.col3 = fltr.col3
SET
  A.col1 = 'abc',
  A.col2 = 'xyz',
  B.col1 = fltr.col1,
  B.col2 = fltr.col2
WHERE
  A.col3 = '1'
;
SELECT * FROM A;


col1
col2
col3


abc
xyz
1


SELECT * FROM B;


col1
col2
col3


a
x
1

b
y
2

c
z
3

col1	col2	col3
null	null	1
null	null	2
null	null	3