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Oracle 9i 中的 SQL�Q��{��_��

Rosen — Tue, 20 Sep 2005 12:05:00 GMT

�W�一�?nbsp; 基本SELECT 语句

ORACLE数据库的体系�l�构�?BR>SYS和SYSTEM用户�?/P>

SQL语句不区分大��写�?BR>‘’和””的区别�?BR>字符串区分大��写�?/P>

NULL倹{�?BR>联接�q�算�W�： ||
旉��的默认格式�ؓDD-MON-YY�?/P>

SELECT * FROM TAB;

字段别名
SELECT job_title AS Title, min_salary AS “Minimum Salary�?FROM jobs;

保证唯一�?BR>SELECT DISTINCT department_id,job_id FROM employees;

DUAL�?BR>SELECT SYSDATE, USER FROM DUAL;

不等�?!=�?lt;>或^=)
SELECT first_name || �?�?|| last_name “Name�?commission_pct FROM employees
WHERE commission_pct != 0.35 ;

<=(��于�{�于)
SELECT first_name || �?�?|| last_name “Name�?commission_pct FROM employees
WHERE commission_pct <= 0.35 ;

>=(大于�{�于)
SELECT first_name || �?�?|| last_name “Name�?commission_pct FROM employees
WHERE commission_pct >= 0.35 ;

ANY(相当于OR)
SELECT first_name || �?�?|| last_name “Name�?department_id FROM employees
WHERE department_id <= ANY (10,15,20,25);

ALL(相当于AND)
SELECT first_name || �?�?|| last_name “Name�?department_id FROM employees
WHERE department_id >= ALL (80,90,100);

IN �?NOT IN
SELECT first_name,last_name,department_id FROM employees
WHERE department_id IN (10,20,90);

IN 相当�?=ANY�?/P>

SELECT first_name,last_name,department_id FROM employees
WHERE department_id NOT IN
(10,30,40,50,60,80,90,110,100);

NOT IN 相当�?!=ALL�?/P>

注意�Q�last_name NOT IN(‘Smith�?’Thomas�?NULL)
不返回�Q何记录�?BR>��M��与NULL值的比较都是NULL倹{�?/P>

BETWEEN
SELECT first_name,last_name,salary FROM employees WHERE salary BETWEEN 5000 AND 6000;

EXISTS
SELECT last_name,first_name,department_id FROM employees e
WHERE EXISTS (SELECT 1 FROM departments d
WHERE d.department_id = e.department_id
AND d.department_name=’Administration�?;

IS NULL和IS NOT NULL
SELECT last_name,department_id FROM employees WHERE department_id IS NULL;

LIKE
SELECT first_name,last_name FROM employees WHERE first_name LIKE ‘Su%�?
AND last_name NOT LIKE ‘S%�?
%、_的含义�?/P>

SELECT job_id,job_title FROM jobs WHERE job_id LIKE ‘AC\_%�?ESCAPE ‘\�?

�l�果集的排序
SELECT first_name || �?�?|| last_name “Employee Name�?FROM employees WHERE department_id =90 ORDER BY last_name;
ASC、DESC�?BR>SELECT first_name,hire_date,salary,manager_id mid FROM employees WHERE department_id IN (110,100) ORDER BY mid ASC,salary DESC, hire_date;

错误�Q�SELECT DISTINCT ‘Region �?|| region_id FROM countries ORDER BY region_id;
正确�Q�SELECT DISTINCT ‘Region �?|| region_id FROM countries
ORDER BY ‘Region �?||region_id;

SELECT first_name,hire_date,salary,manager_id mid FROM employees WHERE department_id IN (110,100) ORDER BY 4,2,3;

NULL的排�?BR>默认情况�?升序排列中NULL值排在最后�?BR>SELECT last_name,commission_pct FROM employees WHERE last_name LIKE ‘R%�?BR>ORDER BY commission_pct ASC, last_name DESC;

SELECT last_name,commission_pct FROM employees WHERE last_name LIKE ‘R%�?BR>ORDER BY commission_pct ASC NULLS FIRST, last_name DESC;

CASE 表达�?9i新增)
SELECT country_name,region_id,
CASE region_id WHEN 1 THEN ‘Europe�?BR> WHEN 2 THEN ‘America�?BR>WHEN 3 THEN ‘Asia�?BR>ELSE ‘Other�?END Continent
FROM countries WHERE country_name LIKE ‘I%�?

SELECT first_name,department_id,salary,
CASE WHEN salary < 6000 THEN ‘Low�?BR> WHEN salary < 10000 THEN ‘Medium�?BR> WHEN salary >= 10000 THEN ‘High�?END Category
FROM employees WHERE department_id <=30 ORDER BY first_name;

�W�二�?nbsp; SQL * Plus的��?/FONT>
SQL * Plus的常用命令�?BR>

�W�三�?nbsp; Oracle 9i 中的函数

NVL
SELECT first_name,last_name,salary,bonus,salary + bonus total_comp FROM employees;

SELECT first_name,last_name,salary,bonus,salary + NVL(bonus,0)
total_comp FROM employees;

NVL2(9i新增)
SELECT first_name,last_name,salary,bonus, NVL2(bonus,salary + bonus,salary)
total_comp FROM employees;

字符串函�?BR>SELECT ASCII(‘A�? Big_A,ASCII(‘z�? Little_z FROM dual;
SELECT CHR(65),CHR(223) FROM dual;
SELECT CONCAT(‘Peter�?’Mackovicky�? FROM dual;
SELECT INITCAP(‘the three musketeers�? book_title FROM dual;
SELECT INSTR(‘Mississippi�?’i�?3,3) test1, INSTR(‘Mississippi�?’i�?1,3) test2
INSTR(‘Mississippi�?’i�?-2,3) test3 FROM dual;

INSTRB
SELECT LENGTH(‘the three musketeers�? title_length FROM dual;
LENGTHB
LOWER
SELECT LPAD(‘Yes�?7,�?�? FROM dual;
SELECT LTRIM(‘Mississippi�?’Mis�? test1, LTRIM(‘RPadded �? test2,
LTRIM(�?nbsp; RPadded�? test3, LTRIM(�?nbsp; RPadded�?’Z�? test4 FROM dual;

数学函数
ABS、ACOS、ASIN、ATAN、ATAN2、BITAND、CEIL、COS、COSH、EXP、FLOOR、LN、LOG、MOD、POWER、SIGN、SIN、SINH、SQRT、TAN、TANH�?BR>ROUND=TRUNC
SELECT TRUNC(123.456,2) pos, TRUNC(123.456,-1) neg FROM dual;

日期函数
ADD_MONTHS、LAST_DAY、MONTH_BETWEEN、NEXT_TIME、NEXT_DAY、ROUND、SYSDATE�?/P>

转换函数
CHARTOROWID、CONVERT、HEXTORAW、NLS_CHARSET_ID、NLS_CHARSET_NAME�?BR>RAWTOHEX、ROWIDTOCHAR、TO_CHAR�?TO_DATE�?TO_ LABEL�?TO_MULTI_BYTE�?BR>TO_NUMBER、TO_SINGLE_BYTE�?/P>

SELECT TO_CHAR(SYSDATE,’yyyy-mm-dd hh24:mi:ss�? FROM dual;
SELECT TO_CHAR(SYSDATE,’month�? FROM dual;
SELECT TO_CHAR(SYSDATE,’SSSSS�? FROM dual;

INSERT INTO demo(demo_key,date_col)
VALUES (1,TO_DATE(�?004-7-1�?’yyyy-mm-dd�?);

其它函数
SELECT COALESCE(NULL,’Oracle�?�?4�? string_type,
COALESCE(3,14,COS(0)) bnr_type FROM dual;
�q�回�W�一个非NULL倹{�?/P>

SELECT DECODE(rating,null,1000,’C�?2000,’B�?3000.’D�?4000,5000) FROM accts;

SELECT USER,UID FROM dual;

GREATEST、LEAST�?/P>

SELECT ename,mgr,comm,NULLIF(comm,0) test1 FROM scott.emp
WHERE empno IN(7844,7839,7654,7369); (9i新增)
如果x1=x2,�q�回NULL。否则x1�?/P>

SELECT SYS_CONTEXT(‘USERENV�?’IP_ADDRESS�? FROM dual; (9i新增)

USERENV函数�?i中停用，��用SYS_CONTEXT函数�?/P>

SELECT VSIZE(user),user FROM dual;

�W�四�?nbsp; 分组汇总语�?/STRONG>

GROUP BY 语句
SELECT cust_state_province, count(*) customer_count
FROM sh.customers GROUP BY cust_state_province;
重点�Q�GROUP BY 语句中SELECT后字�D늚�限制�Q�只能是分组字段和集合函数�?BR>GROUP BY的结果集排序�?/P>

SELECT deptno,MIN(sal),MAX(sal) FROM emp WHERE job=’CLERK�?BR>GROUP BY deptno; (注意此处与SQL Server不同!)

SELECT cust_state_province, count(*) customer_count
        FROM sh.customers GROUP BY cust_state_province ORDER BY COUNT(*) DESC;
或：SELECT cust_state_province, count(*) customer_count
        FROM sh.customers GROUP BY cust_state_province ORDER BY 2 DESC;

�~�定表的一个数据块中��^均有多少行数据：
SELECT AVG(row_count ),MAX(row_count),MIN(row_count)
FROM (SELECT count(*) row_count FROM employees GROUP BY SUBSTR(rowid,1,15));

HAVING
SELECT t.fiscal_month_desc,s.channel_id,SUM(s.quantity_sold),SUM(s.amount_sold)
FROM sh.times t,sh.sales s WHERE t.time_id = s.time_id AND s.promo_id <> 9999
GROUP BY t.fiscal_month_desc,s.channel_id HAVING SUM(s.amount_sold) > 2000000;
HAVING=WHERE�?/P>
错误�Q?BR>SELECT t.fiscal_month_desc,s.channel_id,SUM(s.quantity_sold),SUM(s.amount_sold)
FROM sh.times t,sh.sales s WHERE t.time_id = s.time_id AND s.promo_id <> 9999 AND SUM(s.amount_sold) > 2000000 GROUP BY t.fiscal_month_desc,s.channel_id;

CUBE和ROLLUP
SELECT cust_gender gender,NVL(cust_marital_status,’unknown�? marital_status,COUNT(*)
FROM sh.customers GROUP BY cust_gender, NVL(cust_marital_status,’unknown�?;

SELECT cust_gender gender,NVL(cust_marital_status,’unknown�? marital_status,COUNT(*)
FROM sh.customers GROUP BY cust_gender, ROLLUP(NVL(cust_marital_status,’unknown�?));

SELECT cust_gender gender,NVL(cust_marital_status,’unknown�? marital_status,COUNT(*)
FROM sh.customers GROUP BY ROLLUP(cust_gender, NVL(cust_marital_status,’unknown�?));

SELECT cust_gender gender,NVL(cust_marital_status,’unknown�? marital_status,COUNT(*)
FROM sh.customers GROUP BY CUBE(cust_gender, NVL(cust_marital_status,’unknown�?));

嵌套函数
SELECT deptno,GREATEST(COUNT(DISTINCT job),COUNT(DISTINCT mgr)) cnt,
       COUNT(DISTINCT job ) jobs,   COUNT(DISTINCT mgr) mgrs
FROM emp GROUP BY deptno;

SELECT MAX(COUNT(DISTINCT job)) FROM emp GROUP BY deptno;

集合函数
SELECT empno,sal FROM scott.emp WHERE deptno=20 ORDER BY sal;

DISTINCT和ALL的区�?BR>SELECT AVG(sal) avg, AVG(ALL sal) avg_all,AVG(DISTINCT sal) avg_dist,
COUNT(sal) cnt, COUNT(DISTINCT sal) cnt_dist,SUM(sal) sum_all,SUM(DISTINCT sal ) sum_dist FROM scott.emp WHERE deptno=20;

默认是ALL�?/P>
SELECT job_id,AVG(salary) FROM hr.employees WHERE job_id LIKE ‘AC%�?GROUP BY job_id;

SELECT COUNT(*) emp_count,
       COUNT(DISTINCT department_id) dept_count,
       COUNT(ALL department_id) not_null_dept_count FROM hr.employees;

SELECT cust_gender gender, NVL(cust_marital_status,’unknown�? marital_status,
COUNT(*) emp_count, GROUPING(cust_gender) gender_superagg,
GROUPING(NVL(cust_marital_status,’unknown�?) martial_superagg
FROM sh.customers GROUP BY CUBE(cust_gender, NVL(cust_marital_status,’unknown�?);

Create table tmp as
SELECT cust_gender gender, NVL(cust_marital_status,’unknown�? marital_status,
COUNT(*) emp_count, GROUPING(cust_gender) gender_superagg,
GROUPING(NVL(cust_marital_status,’unknown�?) martial_superagg
FROM sh.customers GROUP BY CUBE(cust_gender, NVL(cust_marital_status,’unknown�?);

�W�五�?nbsp;       联接语句

Oracle 9i中新增加了JOIN子句�Q�以�W�合 ANSI SQL 1999标准�?/P>
对等联接(内联�?
Oracle语法�Q?BR>SELECT locations.location_id,city,department_name FROM locations,departments
WHERE locations.location_id = departments.location_id;

SELECT locations.location_id,city,department_name FROM locations,departments
WHERE locations.location_id = departments.location_id AND country_id != ‘US�?

使用表的别名
SELECT l.location_id,city,department_name FROM
locations l,departments d WHERE l.location_id = d.location_id AND country_id != ‘US�?

当��用表的别名时�Q�只能用别名来限定表名�?BR>错误�Q�SELECT locations.location_id,city,department_name FROM
locations l,departments d WHERE locations.location_id = d.location_id;

ANSI语法�Q?BR>NATURAL JOIN
SELECT location_id,city,department_name FROM locations NATURAL JOIN departments;
自动使用两个表的同名字段�q�行联接�?BR>不要用表名或表的别名来限定列名�?/P>
SELECT * FROM regions NATURAL JOIN countries;

SELECT region_name,country_name,city FROM regions NATURAL JOIN countries
NATURAL JOIN locations;
�{��h于：SELECT region_name,country_name,city FROM regions,countries,locations
WHERE regions.region_id = countries.region_id AND
countries.country_id= locations.country_id;

JOIN �?USING
当两个表的共同字�D�|��据类型不同时�?BR>SELECT location_id,city,department_name FROM locations JOIN departments USING(location_id);

SELECT region_name,country_name,city FROM regions
JOIN countries USING(region_id)
JOIN locations USING(country_id);

SELECT region_name,country_name,city FROM regions
JOIN countries USING(region_id)
JOIN locations USING(country_id)
WHERE country_id = ‘US�?
ORDER BY 1;

JOIN ON
SELECT region_name,country_name,city FROM regions r
JOIN countries c ON r.region_id = c.region_id
JOIN locations l ON c.country_id= l.country_id
WHERE country_id = ‘US�?

SELECT first_name,department_name,city
FROM employees e JOIN departments d ON (e.department_id = d.department_id)
JOIN locations l ON (d.location_id = l.location_id);

�W�卡��乘�U?交叉联接)
Oracle语法�Q?BR>SELECT region_name,country_name FROM regions,countries WHERE countries.country_id LIKE ‘I%�?
ANSI 语法�Q?BR>SELECT region_name,country_name FROM regions CROSS JOIN countries
WHERE countries.country_id LIKE ‘I%�?

外联�?非对�{�联�?
Oracle语法�Q?BR>SELECT c.country_name,l.city FROM countries c ,locations l WHERE c.country_id = l.country_id(+);

select ename,emp.deptno,dname from emp,dept where emp.deptno(+)=dept.deptno(+);

外联接符(+)要用于所有的条�g�?BR>SELECT c.country_name,l.city FROM countries c ,locations l WHERE c.country_id = l.country_id(+) AND l.city LIKE ‘B%�?

SELECT c.country_name,l.city FROM countries c ,locations l WHERE c.country_id = l.country_id(+) AND l.city(+) LIKE ‘B%�?

外联接符(+)不能用于OR和IN�?BR>错误�Q�SELECT c.country_name,l.city FROM countries c ,locations l WHERE c.country_id = l.country_id(+) OR l.city(+) LIKE ‘B%�?

正确�Q�SELECT c.country_name,l.city FROM countries c ,locations l WHERE c.country_id = l.country_id(+) AND c.country_name IN (‘India�?’Israel�?;

ANSI语法�Q?BR>左外联接
SELECT c.country_name,l.city FROM countries c LEFT OUTER JOIN locations l ON
c.country_id = l.country_id;

select ename,emp.deptno,dname from emp LEFT OUTER JOIN dept ON emp.deptno=dept.deptno;
OUTER是可选的�?BR>SELECT country_name,city FROM countries LEFT JOIN locations USING(country_id);
SELECT country_name,city FROM countries NATURAL LEFT JOIN locations;

叛_��联接
SELECT country_name,city FROM locations NATURAL RIGHT OUTER JOIN countries;

SELECT c.country_name,l.city FROM locations l RIGHT JOIN countries c ON
c.country_id = l.country_id;

完全外联�?9i新增)
SELECT e.employee_id,e.last_name,d.department_id,d.department_name
FROM employees e FULL OUTER JOIN departments d ON (e.department_id = d.department_id)

错误�Q�select ename,emp.deptno,dname from emp,dept where emp.deptno(+)=dept.deptno(+);

自联�?BR>用于层次型数据库�?BR>SELECT e.last_name Employee, m.last_name Manager FROM employees e ,employees m
WHERE m.employee_id = e.manager_id;

SELECT e.last_name Employee, m.last_name Manager FROM employees e INNER JOIN
employees m ON m.employee_id = e.manager_id;

�W�六�?nbsp;       集合语句和子查询

集合语句�Q�把多个SELECT语句的结果集合�ƈ成一个结果集�?BR>UNION ALL 合�ƈ多个�l�果集，不消除重复倹{�?BR>UNION     合�ƈ多个�l�果集，消除重复倹{�?BR>INTERSECT
MINUS

SELECT last_name, hire_date FROM employees WHERE department_id = 90;
SELECT last_name, hire_date FROM employees WHERE last_name LIKE ‘K%�?

SELECT last_name, hire_date FROM employees WHERE department_id = 90
UNION ALL
SELECT last_name, hire_date FROM employees WHERE last_name LIKE ‘K%�?

SELECT last_name, hire_date FROM employees WHERE department_id = 90
UNION
SELECT last_name, hire_date FROM employees WHERE last_name LIKE ‘K%�?

SELECT last_name, hire_date FROM employees WHERE department_id = 90
INTERSECT
SELECT last_name, hire_date FROM employees WHERE last_name LIKE ‘K%�?

SELECT last_name, hire_date FROM employees WHERE department_id = 90
MINUS
SELECT last_name, hire_date FROM employees WHERE last_name LIKE ‘K%�?

错误�Q?BR>SELECT last_name, hire_date FROM employees WHERE department_id = 90 ORDER BY last_name
MINUS
SELECT first_name, hire_date FROM employees WHERE last_name LIKE ‘K%�?ORDER BY first_name;

SELECT last_name, hire_date “Join Date�?FROM employees WHERE department_id = 90 MINUS
SELECT first_name, hire_date FROM employees WHERE last_name LIKE ‘K%�?ORDER BY last_name, “Join Date�?

SELECT last_name, hire_date “Join Date�?FROM employees WHERE department_id = 90 MINUS
SELECT first_name, hire_date FROM employees WHERE last_name LIKE ‘K%�?ORDER BY 1,2;

子查�?BR>子查询的特征�Q?nbsp; 子查询要加括受��?BR>             分�ؓ嵌套子查询和相关子查询�?区别�Q�子查询里是否包含联接�?
             分�ؓ单值和多倹{�?BR>             相关子查询可用联接语句代�ѝ�?/P>
单值嵌套子查询的例子：
SELECT lastname,firstname,salary FROM employees
WHERE salary = (SELECT MAX(salary) FROM employees);

SELECT lastname,firstname,salary FROM employees
WHERE department_id = (SELECT department_id FROM departments WHERE department_name=’Accounting�?;

多值嵌套子查询的例子：
SELECT lastname,firstname,salary FROM employees
WHERE department_id = (SELECT department_id FROM departments WHERE first_name=’John�?;

相关子查询的例子�Q?BR>SELECT department_id,last_name,salary FROM employees e1 WHERE salary =
        (SELECT MAX(salary) FROM employees e2 WHERE e1.department_id = e2.department_id);

比较�Q�SELECT department_id,last_name,salary FROM employees WHERE salary =
        (SELECT MAX(salary) FROM employees );

SELECT last_name,first_name, department_id FROM employees e1 WHERE EXISTS
        (SELECT ‘x�?FROM employees e2 WHERE first_name= ‘John�?AND e1.department_id = e2.department_id);

子查询用在case表达式中�Q?BR>SELECT city,country_id,(CASE
      WHEN country_id IN
(SELECT country_id FROM countries WHERE country_name = ‘India�? THEN ‘Indian�?BR>ELSE ‘Non_Indian�?BR>END) “INDIA?�?BR>FROM locations WHERE city LIKE ‘’B%;

子查询用在SELECT子句中：
SELECT last_name,department_id,
     (SELECT MAX(salary) FROM employees sq WHERE sq.ddepartment_id = e.department_id) HSAL FROM employees e WHERE last_name LIKE ‘R%�?

UPDATE employees e1
SET salary = (SELECT MAX(salary) FROM employees e2 WHERE e1.department_id= e2.department_id);

DELETE FROM employees e WHERE salary <(SELECT AVG(salary) FROM employees WHERE department_id= e.department_id);

INSERT INTO employee_archive SELECT * FROM employees;

INSERT INTO departments(department_id,department_name) VALUES
((SELECT MAX(department_id) + 10 FROM departments),’EDP�?;

可以在INSERT、UPDATE、DELETE语句中��用一个子查询来代替表名�?BR>DELETE FROM (SELECT * FROM departments WHERE department_id < 20) WHERE department_id =10;

DELETE FROM (SELECT * FROM department WHERE department_id < 20) WHERE department_id =10;

INSERT INTO (SELECT department_id,department_name FROM department WHERE department_id < 20) VALUES (35, ‘MARKETING�?;

WITH READ ONLY�?WITH CHECK OPTION�?/P>
INSERT INTO (SELECT department_id,department_name FROM departments WHERE department_id < 20 WITH CHECK OPTION) VALUES (45, ‘MARKETING�?;

�W�七�?nbsp;       修改数据(INSERT、UPDATE、DELETE语句)

INSERT语句
INSERT INTO checking(account_id,create_date,balance)
VALUES(‘Kiesha�?SYSDATE,5000);

INSERT INTO brokerage(account_id,create_date,balance)
SELECT account_id, SYSDATE,0 FROM checking WHERE account_type =’C�?

INSERT INTO e_checking
SELECT * FROM checking WHERE account_type =’C�?

UPDATE语句
UPDATE order_rollup SET (qty,price) = (SELECT SUM(qty),SUM(price) FROM order_lines
       WHERE customer_id=’KHOL�? WHERE customer_id =’KHOL�?AND order_period= TO_DATE(�?1-Oct-2001�?;

UPDATE order_rollup SET phone = �?23456�?fax=�?34567�?WHERE customer_id=’KHOL�?/P>
DELETE语句
DELETE FROM customers WHERE customer_id = ‘GOMEZ�?
DELETE FROM order_staging;
DML
TRUNCATE语句
TRUNCATE TABLE order_staging;
TRUNCATE语句是一个DDL语句�?/P>
SELECT �?FOR UPDATE 语句

事务语句
COMMIT、COMMIT WORK�?BR>ROLLBACK�?BR>SAVEPOINT�?/P>
DDL与语句不需要提交�?/P>
RENAME语句
rename T1 to T2;

CREATE TABLE �?AS SELECT …语�?BR>CREATE TABLE emp_tmp AS SELECT*FROM emp WHERE deptno=10;
复制表：create table t2 as select * from t1;
复制表的�l�构�Q�create table t2 as select*from t1 where 1=2;

Top n 语句
SELECT last_name,salary FROM employees WHERE rownum <=5 ORDER BY salary DESC;

.........................................................................................................................
useraccount表，主键为userid�Q�有一个字�D��ؓ手机��L��mobilephone

如果重复的记录的比例不是很大

delete useraccount where rowid in (
select rid from
(select rowid rid,row_number() over(partition by mobilephone order by userid desc) rn from useraccount )
where rn > 1) ;

Rosen 2005-09-20 20:05 发表评论

Rosen — Tue, 20 Sep 2005 12:04:00 GMT
/**
* @author imagebear
*/

日期问题
1、获取服务器端当前日期：

<%@ page import="java.util.Date"%>
<%
Date myDate = new Date();
%>

2、获取当前年、月、日�Q?BR>

<%@ page import="java.util.Date"%>

<%
Date myDate = new Date();
int thisYear = myDate.getYear() + 1900;//thisYear = 2003
int thisMonth = myDate.getMonth() + 1;//thisMonth = 5
int thisDate = myDate.getDate();//thisDate = 30
%>

3、按本地时区输出当前日期

<%@ page import="java.util.Date"%>
<%
Date myDate = new Date();
out.println(myDate.toLocaleString());
%>

输出�l�果为：
2003-5-30
4、获取数据库中字�D�名为”publish_time“、类型�ؓDatetime的�?BR>

<%@ page import="java.util.Date"%>
<%
...�q�接数据�?..
ResultSet rs = ...
Date sDate = rs.getDate("publish_time");
%>
[code]
5、按照指定格式打印日�?BR>[code]
<%@ page import="java.util.Date"%>
<%@ page import="java.text.DateFormat"%>
<%
Date dNow = new Date();

SimpleDateFormat formatter = new SimpleDateFormat("E yyyy.MM.dd 'at' hh:mm:ss a zzz");
out.println("It is " + formatter.format(dNow));
%>

输出的结果�ؓ�Q?BR>It is 星期�?2003.05.30 at 11:30:46 上午 CST
(更�ؓ详尽的格式符可��参看SimpleDateFormat�c?
6、将字符串�{换�ؓ日期

<%@ page import="java.util.Date"%>
<%@ page import="java.text.DateFormat"%>
<%
String input = "1222-11-11";
SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd");
Date t = null;
try{
t = formatter.parse(input);
out.println(t);
}catch(ParseException e){
out.println("unparseable using " + formatter);
}
%>

输出�l�果为：
Fri Nov 11 00:00:00 CST 1222
7、计��日期之间的间隔

<%@ page import="java.util.Date"%>
<%@ page import="java.text.DateFormat"%>
<%
String input = "2003-05-01";
SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd");
Date d1 = null;
try{
d1 = formatter.parse(input);
}catch(ParseException e){
out.println("unparseable using " + formatter);
}

Date d2 = new Date();

long diff = d2.getTime() - d1.getTime();
out.println("Difference is " + (diff/(1000*60*60*24)) + " days.");
%>

输出�l�果为：
Difference is 29 days.
8、日期的加减�q�算
�Ҏ��Q�用Calendar�cȝ��add()�Ҏ��

<%@ page import="java.util.*"%>
<%@ page import="java.text.*"%>
<%
Calendar now = Calendar.getInstance();
SimpleDateFormat formatter = new SimpleDateFormat("E yyyy.MM.dd 'at' hh:mm:ss a zzz");
out.println("It is now " + formatter.format(now.getTime()));
now.add(Calendar.DAY_OF_YEAR,-(365*2));
out.println("
");
out.println("Two years ago was " + formatter.format(now.getTime()));
%>

输出�l�果为：
It is now 星期�?2003.05.30 at 01:45:32 下午 CST
Two years ago was 星期�?2001.05.30 at 01:45:32 下午 CST
9、比较日�?BR>�Ҏ��Q�用equals()、before()、after()�Ҏ��

<%@ page import="java.util.*"%>
<%@ page import="java.text.*"%>
<%
DateFormat df = new SimpleDateFormat("yyy-MM-dd");
Date d1 = df.parse("2000-01-01");
Date d2 = df.parse("1999-12-31");

String relation = null;
if(d1.equals(d2))
relation = "the same date as";
else if(d1.before(d2))
relation = "before";
else
relation = "after";
out.println(d1 +" is " + relation + ' ' + d2);
%>

输出�l�果为：
Sat Jan 01 00:00:00 CST 2000 is after Fri Dec 31 00:00:00 CST 1999
10、记录一件事所��p��的时�?BR>�Ҏ��Q�调用两�ơSystem.getTimeMillis()�Ҏ��Q�求差�?BR>

<%@ page import="java.text.*"%>
<%
long t0,t1;
t0 = System.currentTimeMillis();
out.println("Cyc starts at " + t0);
int k = 0;
for(int i =0;i<100000;i++){
k += i;
}
t1 = System.currentTimeMillis();
out.println("
");
out.println("Cyc ends at " + t1);
out.println("
");
out.println("This run took " + (t1-t0) + "ms.");
%>

输出�l�果为：
Cyc starts at 1054275312432
Cyc ends at 1054275312442
This run took 10ms.

其它�Q�如何格式化��数

<%@ page import="java.text.*"%>
<%
DecimalFormat df = new DecimalFormat(",###.00");
double aNumber = 33665448856.6568975;
String result = df.format(aNumber);
out.println(result);
%>

输出�l�果为：
33,665,448,856.66

Rosen 2005-09-20 20:04 发表评论