如果我有一张桌子
CREATE TABLE users (
id int(10) unsigned NOT NULL auto_increment,
name varchar(255) NOT NULL,
profession varchar(255) NOT NULL,
employer varchar(255) NOT NULL,
PRIMARY KEY (id)
)
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我希望获得所有独特的profession字段值,更快(或推荐):
SELECT DISTINCT u.profession FROM users u
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要么
SELECT u.profession FROM users u GROUP BY u.profession
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?