計算兩日期間隔天數
values (days(current date) - days('2014-09-01'))
去出某一字符串的的一個單詞，空格為分隔符
select substr(title,1,instr(title,' ')-1) from titles
將字符串的一個空格替換為'--hello--'
select substr(title,1,locate(' ',title)-1) || '--hello--' || substr(title,locate(' ',title)+1) from titles
db2生成隨機數
select case when price is null then INT(rand()*100) else price end from titles
兩日期相差多少月，64代表月。參數可以更改求出周，小時等等。
select TIMESTAMPDIFF(64,char(TIMESTAMP(CURRENT DATE) - TIMESTAMP(pubdate)) )from titles
有關db2日期操作可參考此博客。
http://www.cnblogs.com/wanghonghu/archive/2012/05/25/2518604.html 建立數據表，有generated always列
create table t1
(
c1 char(30),
c2 double,
c3 int not null generated always as identity
(start with 100, increment by 5)
)
第一次更新用insert into t1(c1,c2,c3) values('123',34,default)
以后用 insert into t1(c1,c2) values('hi',45)
如果是generated by default
create table t1
(
c1 char(30),
c2 double,
c3 int not null generated by default as identity
(start with 100, increment by 5)
)
如果插入時只有兩個參數，就按默認的來
如果三個參數，就是插入的那個數
默認生成的第三個數可以修改，系統會有記錄，即使修改了也會從上一次的默認位置開始疊加。不會再回到100.
--select * from authors
--select au_lname, au_fname from authors where state ='CA'
--select * from publishers
--select distinct state from publishers
--select *from titles
--select * from titles where price is null
-- select case when price is null then 0 else price end from titles-- it works!!!!!!!!!!
-- 4 Functions
--select varchar_format(current date - date('2011-01-01') + date, 'DD-MM-YY') as newDate,
-- varchar_format(date,'DD-MM-YY') as olddate from sales
--values current date - date('2014-01-01') + date('2014-01-02')
--select *from roysched
--select hex(lorange) from roysched
--select * from titles where price in (20,19) -- in one shot ZANZANZANZANZAN!!!
select
case type when 'business' then Title else 'other' end from titles 聯系條件語句并顯示成不同的屬性-----------------------------------------------------------------------------------------------
--select * from authors
--select au_lname, au_fname from authors where state ='CA'
--select * from publishers
--select distinct state from publishers
--select *from titles
--select * from titles where price is null
-- select case when price is null then 0 else price end from titles-- it works!!!!!!!!!!
-- 4 Functions
--select varchar_format(current date - date('2011-01-01') + date, 'DD-MM-YY') as newDate,
-- varchar_format(date,'DD-MM-YY') as olddate from sales
--values current date - date('2014-01-01') + date('2014-01-02')
--select *from roysched
--select hex(lorange) from roysched
--select * from titles where price in (20,19) -- in one shot ZANZANZANZANZAN!!!
--select case type when 'business' then Title else 'other' end from titles
--select syscolumns.length from syscolumns where syscolumns.id = 'titles' and syscolumns.name = 'title'
--5 Grouping
--select (days(max(pubdate)) - days(min(pubdate)) )/365 from titles
--select title from titles order by length(title)
--select *from titles
--select count(*) from authors group by city
--select title from titles where length(title) = (select max(length(title)) from titles)
--select coalesce(price,0) from titles -- yuan lai bushi yong is null shi yong zhe ge a!!!!
--select length(price) from titles
/*
select title from titles where length(title) >= all
(
select length(title) from titles
)
*/
--select pubdate from titles
/*
select title,pubdate from titles where pubdate >= all
(
select pubdate from titles
)
*/
--select count(*) from sales group by stor_num
--select * from sales
--select * from publishers
--select * from titles as a inner join publishers as b on a.pub_id = b.pub_id
--select title,city,a.pub_id from titles as a inner join publishers as b on a.pub_id = b.pub_id where city not in ('Boston')
--select * from psales
/*
select b.ord_num,b.discount,d.discounttype from psales as a inner join salesdetail as b on a.stor_id = b. stor_id and a.ord_num = b.ord_num
inner join stores as c on a.stor_id = c.stor_id inner join discounts as d on c.stor_id = d.stor_id order by b.ord_num
*/
--select * from authors
--select * from publishers
--select * from authors as a inner join publishers as b on a.city = b.city
--select sum(qty) from salesdetail
--select pub_name, count(distinct type) from publishers as a inner join titles as b on a.pub_id = b.pub_id group by pub_name
--select *from titleauthor
--7 Sub-Queries
/*
select pub_name from publishers where pub_id in
(
select pub_id from titles
)
*/
--select * from publishers
--nice !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
/*
select type,title,t1.price
from titles as t1
where price > (select avg(price) from titles as t2 where t2.type = t1.type)
*/
-- nice !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
select
title,t1.price
from
titles as t1
where
price > all(select coalesce(price,0) from titles as t2 where t2.type != t1.type)
--select * from titles
--select t1.type,t1.title,t1.price,(select avg(price) from titles as t2 where t2.type = t1.type)
--from titles as t1
--where price > (select avg(price) from titles as t2 where t2.type = t1.type)
--select avg(price) from titles
--select abs(13.93750000000000000000000000- price) from titles
--select coalesce(abs((select avg(price) from titles) - price),0) from titles
--select count(*) as ANS from SB_AUCTION where (days(enddate) - days(startdate) < 10)
/*
select
description, enddate, reserve from SB_Auction inner join sb_item on SB_Auction.itemid = sb_item.itemid
where (date('2011-02-20') >= startdate and date('2011-02-20') <= enddate) order by reserve desc
*/
--select * from sb_bid
--select name from (sb_bid as a inner join sb_auction as b on a.bidder = b.userid) inner join sb_user as c on b.userid = c.userid group by name
--select * from authors
--select newA.name from
--(
--select name,c.itemid from (sb_user as a inner join sb_auction as b on a.userid = b.userid)
-- inner join sb_item as c on b.itemid = c.itemid
--) AS newA
--select * from sb_auction
/*
create
view weitaol_view
as
select
c.auctionid, max(amount) as winning_bid from sb_auction as a inner join sb_user as b on a.winnerid = b.userid
inner join sb_bid as c on a.auctionid = c.auctionid where a.state = 'sold' group by c.auctionid
*/
--select * from weitaol_view
select
enddate, description,coalesce(name,'==') as name ,coalesce(c.winning_bid,0) as winning_bid
from sb_auction as a inner join sb_item as b on a.itemid = b.itemid
left join sb_user on a.winnerid = sb_user.userid
left join weitaol_view as c on a.auctionid = c.auctionid
/*
select * from sb_auction
*/