摘要： 使用子查询简单子查询SELECT select_listFROM tableWHERE expr operator (SELECT select_list FROM table);子查询可以出现在select,from和where之后，都是可以的。SELECT last_name, salaryFROM employeesWHERE salary > (SELECT salary FROM employees WHERE last_name = 'Abel');SELEC... 阅读全文