信息系统设计与分析 sql.txt

文档介绍：create table ttext(
tID int primary key,
URL varchar(160) not null,
passage nvarchar(3700),
ttime datetime
);
create table extract(
ID int primary key,
tID int references ttext(tID),
parameter varchar(30) not null,
tvalue varchar(30) not null,
unit varchar(10)
)
create view view1 as
select parameter,tvalue,count(*) total from extract group by parameter,tvalue
create view view2 as
select parameter,sum(total) Totals from view1 group by parameter
create view view3 as
select fparameter , ftvalue,convert(real,total)/ tpercent from view1 join view2
on =
create view view4 as
select ,,,
from view3,extract
where view