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CREATE TABLE MyTable (`firstname` VARCHAR(5), `lastname` VARCHAR(3), UNIQUE(firstname, lastname));
✓
INSERT INTO MyTable (`firstname`, `lastname`) VALUES
('jack', 'woo'),
('james', 'poo'),
('james', 'woo'),
('john', 'poo');
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UPDATE MyTable AS t1
SET lastname = 'woo'
WHERE t1.lastname = 'poo'
AND NOT EXISTS (SELECT 1 FROM MyTable t2 WHERE (t2.firstname, t2.lastname) = (t1.firstname, 'woo'));
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DELETE FROM MyTable WHERE lastname = 'poo';
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SELECT * FROM MyTable;
| firstname | lastname |
|---|---|
| jack | woo |
| james | woo |
| john | woo |