的信息。
方式一(通用型):SELECT ... FROM ... WHERESELECT e.last_name,e.department_id,d.department_nameFROM employees e,departments dwhere e.department_id = d.department_id方式二：SELECT ... FROM ... NATURAL JOIN ...有局限性：会自动连接两个表中相同的列(可能有多个:department_id和manager_id)SELECT last_name,department_id,department_nameFROM employeesNATURAL JOIN departments方式三：SELECT ... JOIN ... USING ...有局限性：好于方式二，但若多表的连接列列名不同，此法不合适SELECT last_name,department_id,department_nameFROM employeesJOIN departmentsUSING(department_id)方式四：SELECT ... FROM ... JOIN ... ON ...常用方式，较方式一，更易实现外联接(左、右、满)SELECT last_name,e.department_id,department_nameFROM employees eJOIN departments dON e.department_id = d.department_id--内连接 1） --等值连接 --不等值连接 2） --非自连接 --自连接--外连接 --左外连接、右外连接、满外连接新闻热点
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