MySQL在编程块 - 存储过程,函数和触发器中仅支持IF
语句。因此,你无法做到你想要的那样。
相反,你可以只写一个查询:
INSERT INTO Products (product_id, name, category, manufacturer)
SELECT product_id, name, category, manufacturer
FROM (SELECT 10000 as product_id, 'IphoneZ' as name, null as category, 'appl' as manufacturer) t
WHERE NOT EXISTS (SELECT 1 FROM Products p WHERE p.name = t.name and p.manufacturer = t.manufacturer);
而事实上,最好是有数据库直接执行这种独特性。你可以用一个唯一约束/索引这样做:
CREATE UNIQUE INDEX unq_product_manufacturer_name ON product(manufacturer, name);
然后,你可以写一个查询做忽略错误:
INSERT INTO Products (product_id, name, category, manufacturer)
VALUES (10000, 'IphoneZ', null, 'appl')
ON DUPLICATE KEY UPDATE category = VALUES(category);
的ON DUPLICATE KEY
没有做任何事情 - 它只是用来避免在插入重复值时返回错误。
双引号代替单引号? – jarlh
阅读说明书 http://dev.mysql.com/doc/refman/5.7/en/exists-and-not-exists-subqueries.html – 2oppin
谷歌搜索你的标题和'mysql':http://stackoverflow.com/5528854 /问题/使用-的-mysqls - 如果存在 - 。请阅读[问]。 – philipxy