Oracle 10g SQL Fundamentals II(学习笔记二第5-6章)

第五章不同时区管理数据
				TIME_ZONE 会话参数值
						时间相对值：
							ALTER SESSION SET TIME_ZONE = '-05:00';
						数据库时间区：
							ALTER SESSION SET TIME_ZONE = dbtimezone;
						操作系统时间区：
							ALTER SESSION SET TIME_ZONE = local;
						区域命名：
							ALTER SESSION SET TIME_ZONE = 'America/New_York';

				CURRENT_DATE:
				        设置时间的格式：
				        ALTER SESSION SET NLS_DATE_FORMAT='DD-MON-YYYY HH24:MI:SS';
						设置时区
						ALTER SESSION SET TIMZE_ZONE='-5:00';
						
						SELECT SESSIONTIMEZONE,CURRENT_DATE FROM DUAL;
						
				
                CURRENT_TIMESTAMP:
						SELECT SESSIONTIMEZONE,CURRENT_TIMESTAMP FROM DUAL;
						
                LOCALTIMESTAMP:				
				        SELECT CURRENT_TIMESTAMP,LOCALTIMESTAMP FROMDUAL;
				
				DBTIMEZONE 
						SELECT DBTIMEZONE FROM DUAL;
				SESSIONTIMEZONE
						SELECT SESSIONTIMEZONE FROM DUAL;
						
				获取部分时间的值：
				   select extract(YEAR FROM SYSDATE) FROM DUAL;
				   
				   SELECT last_name, hire_date, 
						   EXTRACT (MONTH FROM HIRE_DATE)
					FROM employees
					WHERE manager_id = 100;

				TZ_OFFSET
				    select TZ_OFFSET('US/Eastern') from dual;
					select TZ_OFFSET('Europe/London') from dual;
					
				FROM_TZ
				    select FROM_TZ(TIMESTAMP '2000-03-28 08:00:00','3:00') from dual;
					select FROM_TZ(TIMESTAMP '2000-03-28 08:00:00','Australia/North') from dual;
					
				TO_TIMESTAMP
				     SELECT TO_TIMESTAMP ('2000-12-01 11:00:00','YYYY-MM-DD HH:MI:SS')   FROM DUAL;
				TO_TIMESTAMP_TZ 
					 SELECT TO_TIMESTAMP_TZ('1999-12-01 11:00:00 -8:00','YYYY-MM-DD HH:MI:SS TZH:TZM') FROM DUAL;

				
				SELECT hire_date, 
				   hire_date + TO_YMINTERVAL('01-02') AS
				   HIRE_DATE_YMININTERVAL	  
			   FROM   employees
			   WHERE department_id = 20; 
			   
			   
			   
			   
			   SELECT last_name, 
				 TO_CHAR(hire_date, 'mm-dd-yy:hh:mi:ss') hire_date, 
				  TO_CHAR(hire_date + 
				   TO_DSINTERVAL('100 10:00:00'),
					 'mm-dd-yy:hh:mi:ss') hiredate2
				FROM employees;




				第六章子查询
					SELECT	employee_id, manager_id, department_id
					FROM	employees
					WHERE  (manager_id, department_id) IN
										  (SELECT manager_id, department_id
										   FROM   employees
										   WHERE  employee_id IN (199,174))
					AND	employee_id NOT IN (199,174);

                   SELECT employee_id, last_name,
					   (CASE  WHEN department_id =
								 (SELECT department_id
								 FROM departments
					          WHERE location_id = 1800
					            )THEN 'Canada' 
						ELSE 'USA' END
					   ) location
				   FROM   employees;

					SELECT   employee_id, last_name
					FROM     employees e
					ORDER BY (SELECT department_name
							   FROM departments d
								WHERE e.department_id = d.department_id);

					 SELECT last_name, salary, department_id
						FROM   employees outer
						WHERE  salary >             (SELECT AVG(salary)
								  FROM   employees
								  WHERE  department_id =  
								  outer.department_id);

								  
					SELECT e.employee_id, last_name,e.job_id
					FROM   employees e 
					WHERE  2 <= (SELECT COUNT(*)
								 FROM   job_history 
								 WHERE  employee_id = e.employee_id);
								 
								 
					SELECT employee_id, last_name, job_id, department_id
					FROM   employees outer
					WHERE  EXISTS ( SELECT 'X'
									 FROM   employees
									 WHERE  manager_id = 
											outer.employee_id);
											
					SELECT department_id, department_name
					FROM departments d
					WHERE NOT EXISTS (SELECT 'X'
									  FROM   employees
									  WHERE  department_id 
											 = d.department_id);
											 
											 
											 
											 
					UPDATE table1 alias1
					SET    column = (SELECT expression
									 FROM   table2 alias2
									 WHERE  alias1.column =    
											alias2.column);
											
											
					DELETE FROM table1 alias1
					 WHERE  column operator 
						(SELECT expression
						 FROM   table2 alias2
						 WHERE  alias1.column = alias2.column);

					with的语句的使用：
					WITH dept_costs  AS (
					   SELECT d.department_name, SUM(e.salary) AS dept_total
					   FROM    employees e, departments d
					   WHERE   e.department_id = d.department_id
					   GROUP BY d.department_name),
					avg_cost    AS (
					   SELECT SUM(dept_total)/COUNT(*) AS dept_avg
					   FROM   dept_costs)
					SELECT * 
					FROM   dept_costs 
					WHERE  dept_total >
							(SELECT dept_avg 
							 FROM avg_cost)
					ORDER BY department_name;