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-- 創建一個自定義單值類型
create distinct type var_newtype
as decimal(5,2) with comparisons;
-- var_newtype 類型名
-- decimal(5,2) 實際的類型
-- 刪除一個自定義單值類型
drop distinct type var_newtype;
-- 創建一個自定義結構數據類型
create type my_type as(
username varchar(20),
department integer,
salary decimal(10,2))
not final
mode db2sql;
-- 修改自定義結構數據類型,我目前還沒有發現刪除屬性的方法.
alter type my_type
add attribute hiredate date;
-- 刪除自定義結構數據類型
drop type my_type;
-- 獲取系統當前日期
select current date from sysibm.sysdummy1;
select current time from sysibm.sysdummy1;
select current timestamp from sysibm.sysdummy1;
--sysibm.sysdummy1表是一個特殊的內存中的表，用它可以發現如上面演示的 DB2 寄存器的值。您也可以使用關鍵字 VALUES 來對寄存器或表達式求值。
VALUES current date;
VALUES current time;
VALUES current timestamp;
-- VALUES的更多用法
VALUES 2+5;
VALUES 'hello lavasoft!';
values 56
union all
values 45;
values 1,2,3,4,5,6
union all
values 7,8,9,10,11,12
order by 1;
-- 更多變態級DB2 SQL寫法,AnyOneTable表示任意一個存在的表
select 234 from AnyOneTable;
select distinct 234 from AnyOneTable;
select distinct 234 as 1 from AnyOneTable;
select 'DB2變態級的SQL哈哈' from AnyOneTable;
select distinct 'DB2變態級的SQL哈哈' from AnyOneTable;
select distinct 'DB2變態級的SQL哈哈' as 1 from AnyOneTable;
--(嘿嘿,好玩吧,你可以用任意一個表來當sysibm.sysdummy1用.不過不推薦這么做,除非你不記得sysibm.sysdummy1怎么寫了,Oracle中(對應dual)也一樣!哈哈哈哈!)
-- 定義變量,還可以設定默認值,給變量賦值
declare var1 char(2);
declare var2 int default 0;
set var1 = 'aa';
set var2 =23;
--創建一個動態游標變量
declare d_cur integer;
-- 給變量賦值的另一種方法
values expr1, expr2, expr3 into a, b, c;
-- 相當于
set a = expr1;
set b = expr2;
set c = expr3;
-- 還有一種賦值方式
set prodname = (case
when (name is not null) then name
when (namestr is not null) then namestr
else defaultname
end);
-- 相當于
set prodname = coalesce(name, namestr, defaultname);
--這個類似oracle的decode()和nvl()函數的合并.
-- 定義一個游標
declare cur1 cursor with return to client for select * from dm_hy;
declare cur2 cursor for select * from dm_hy; -- 靜態游標
-- 創建數據表,并添加注釋,插入數據.
CREATE TABLE tbr_catalog (
id bigint not null generated by default as identity,
type smallint not null,
name varchar(255),
parentid bigint,
cataloglevel bigint,
description varchar(255),
PRIMARY KEY (id)
);
comment on table tbr_catalog is 'Birt報表目錄表';
comment on column tbr_catalog.ID is '標識';
comment on column tbr_catalog.type is '目錄類型';
comment on column tbr_catalog.name is '目錄名稱';
comment on column tbr_catalog.parentid is '目錄父標識';
comment on column tbr_catalog.cataloglevel is '目錄層次';
comment on column tbr_catalog.description is '目錄描述';
-- 給數據表插入數據
insert into tbr_catalog(id, type, name, parentid, cataloglevel, description)
values (1, 0, '系統報表', 0, 0, '');
insert into tbr_catalog(id, type, name, parentid, cataloglevel, description)
values (2, 1, '用戶報表', 0, 0, '');
-- 創建外鍵
alter table tbr_storage
add constraint fk_tbr_storage
foreign key (catalogid)
references tbr_catalog(id);
-- 更改表,添加列
alter table aaa add sex varchar(1);
-- 更改表,刪除列
alter table aaa drop column sex;
-- 去掉參數前后的空格
rtrim(dm_hy.mc);
-- 定義臨時表,通過已有person表來創建
declare global temporary table gbl_temp
like person
on commit delete rows --提交時刪除數據
not logged -- 不在日志中紀錄
in usr_tbsp -- 選用表空間
-- 此語句創建一個名為 gbl_temp 的用戶臨時表。定義此用戶臨時表 所使用的列的名稱和說明與 person 的列的名稱和說明完全相同。
-- 創建有兩個字段的臨時表
-- 定義一個全局臨時表tmp_hy
declare global temporary table session.tmp_hy
(
dm varchar(10),
mc varchar(10)
)
with replace -- 如果存在此臨時表，則替換
not logged; -- 不在日志里紀錄
-- 給臨時表插入三條數據
insert into session.tmp_hy values('1','1');
insert into session.tmp_hy values('1','1');
insert into session.tmp_hy values('1','1');
-- 通過查詢批量插入數據
inster into tab_bk(select code,name from table book);
-- select ... into的用法
select * into :h1, :h2, :h3, :h4
from emp
where empno = '528671';
-- 語句的流程控制
if() then
open cur1
fetch cur1 into t_equipid;
while(at_end<>1)do
......
set t_temp=0;
end while;
close cur1;
else
......
end if;
-- 外連接
select empno,deptname,projname
from (emplyoee
left outer join project
on respemp=empon)
left outer join department
on mgrno=empno;
-- in、like、order by(... ASC|DESC)的用法
select * from book t
where t.name like '%J_編程%'
and t.code in（'J565333','J565222');
order by t.name asc
-- 匯總表(概念復雜，難以理解，不常用）
create summary table sumy_stable1
as (select workdept,
count(*) as reccount,
sum(salary) as salary,
sum(bonus) as bonus
from employee group by workdept)
data initially deferred
refresh immediate;
-- 使用SQL一次處理一個集合語義
-- （優化前） select語句中每行的過程層和數據流層之間都有一個上下文切換
declare cur1 cursor for col1,col2 from tab_comp;
open cur1;
fetch cur1 into v1,v2;
while SQLCODE<> 100 do
if (v1>20) then
insert into tab_sel values(20,v1);
else
insert into tab_sel values(v1,v2);
end if;
fetch cur1 into v1,v2;
end while;
-- （優化后）沒有過程層和數據流層之間的上下文切換
declare cur1 cursor for col1,col2 from tab_comp;
open cur1;
fetch cur1 into v1,v2;
while SQLCODE<> 100 do
insert into tab_sel(select (case
when col1>20 then 20
else col1
end),
col2
from tab_comp);
fetch cur1 into v1,v2;
end while;
-- DB2函數分三類：列函數、標量函數、表函數
-- 列函數輸入一組數據，輸出單一結果。
-- 標量函數接收一個值，返回另外一個值。
-- 表函數只能用于SQL語句的from字句中，它返回一個表的列，類似于一個已創建的常規表。
-- 下面是個標量函數的例子。
create function (salary int,bonus_percent int)
returns int
language SQL contains SQL
return(
salary * bonus_percent/100
)
-- 下面是表函數
create function get_marks(begin_range int,end_range int)
returns table(cid candidate_id,
number test_id,
score score)
language SQL reads SQL DATA
return
select cid,number,score
from test_taken
where salary between (begin_range) and score(end_range)
example 1: define a scalar function that returns the tangent of a value using the existing sine and cosine functions.
create function tan (x double)
returns double
language sql
contains sql
no external action
deterministic
return sin(x)/cos(x)
example 2: define a transform function for the structured type person.
create function fromperson (p person)
returns row (name varchar(10), firstname varchar(10))
language sql
contains sql
no external action
deterministic
return values (p..name, p..firstname)
example 3: define a table function that returns the employees in a specified department number.
create function deptemployees (deptno char(3))
returns table (empno char(6),
lastname varchar(15),
firstname varchar(12))
language sql
reads sql data
no external action
deterministic
return
select empno, lastname, firstnme
from employee
where employee.workdept = deptemployees.deptno
example 4: define a scalar function that reverses a string.
create function reverse(instr varchar(4000))
returns varchar(4000)
deterministic no external action contains sql
begin atomic
declare revstr, reststr varchar(4000) default '';
declare len int;
if instr is null then
return null;
end if;
set (reststr, len) = (instr, length(instr));
while len > 0 do
set (revstr, reststr, len)
= (substr(reststr, 1, 1) concat revstr,
substr(reststr, 2, len - 1),
len - 1);
end while;
return revstr;
end
example 4: define the table function from example 4 with auditing.
create function deptemployees (deptno char(3))
returns table (empno char(6),
lastname varchar(15),
firstname varchar(12))
language sql
modifies sql data
no external action
deterministic
begin atomic
insert into audit
values (user,
'table: employee prd: deptno = ' concat deptno);
return
select empno, lastname, firstnme
from employee
where employee.workdept = deptemployees.deptno
end