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-（高效） 0.187 SELECT * FROM hr.employees emp --(基础表) WHERE emp.employee_id > 0 AND EXISTS (SELECT 'X' FROM hr.departments dept WHERE DEPT.Department_Id = EMP.Department...

游标 游标分为显示游标和隐示游标。下面有两个实例然码实践这两个例子 cursor c_name(var_name var_type) is|as select ... from ...<--游标的语法-> where... 游标的属性： %isopen<--是否打开-> %found %notfound %rowcount 用法： open...

--触发器 触发器:很耗性能 有两个 :old :new create or replace trigger t_emp_salary after update of salary on hr.employees for each row declare -- local variables here name varchar2(60) ; begin...