由于这些列不可为空，因此对于不希望在语句中提供值的列，必须传递0s而不是nulls，INSERT并使用比较符0代替null：
INSERT INTO stock (price, stock1, stock2) VALUES
('99', '10', 0),
('120', 0, '12')
ON DUPLICATE KEY UPDATE
`stock1-C` = `stock1-C` + (VALUES(stock1) <> 0 AND stock1 <> 0),
stock1 = stock1 + VALUES(stock1),
`stock2-C` = `stock2-C` + (VALUES(stock2) <> 0 AND stock2 <> 0),
stock2 = stock2 + VALUES(stock2)
结果：
然后再次：
INSERT INTO stock (price, stock1, stock2) VALUES
('99', '10', 0),
('120', 0, '12')
ON DUPLICATE KEY UPDATE
`stock1-C` = `stock1-C` + (VALUES(stock1) <> 0 AND stock1 <> 0),
stock1 = stock1 + VALUES(stock1),
`stock2-C` = `stock2-C` + (VALUES(stock2) <> 0 AND stock2 <> 0),
stock2 = stock2 + VALUES(stock2)
结果：
然后：
INSERT INTO stock (price, stock1, stock2) VALUES
('150', '55', 0),
('150', 0, '56')
ON DUPLICATE KEY UPDATE
`stock1-C` = `stock1-C` + (VALUES(stock1) <> 0 AND stock1 <> 0),
stock1 = stock1 + VALUES(stock1),
`stock2-C` = `stock2-C` + (VALUES(stock2) <> 0 AND stock2 <> 0),
stock2 = stock2 + VALUES(stock2)
结果：
然后：
INSERT INTO stock (price, stock1, stock2) VALUES
('150', '10', 0),
('150', 0, '10')
ON DUPLICATE KEY UPDATE
`stock1-C` = `stock1-C` + (VALUES(stock1) <> 0 AND stock1 <> 0),
stock1 = stock1 + VALUES(stock1),
`stock2-C` = `stock2-C` + (VALUES(stock2) <> 0 AND stock2 <> 0),
stock2 = stock2 + VALUES(stock2)
结果：
参见演示。
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