1.注释语句
单行 --
多行 /* */
2.申明变量
declare @lastname nvarchar(30),@firstname nvarchar(20)
3赋值
select @mycounter=20
set @myvar1='this is a test'
set @rows=(select count(*) from authors)
4 if else
if (select avg(price) from titler where type="business")<$20
begin
end
else
begin
end
if [not] exists (select 语句) －－只要检测到一条记录就返回正确结果
句组1
else
句组2
5while
while not exists(select price from titles where price<$30)
begin
update titles
set price=price*1.5
select max(price) from titles
if(select max(price) from titles)>$50
break;
else
continue;
end
6 case
select "作者"=
case state
when "ca" then "来自加利福尼亚州"
when "ks" then "来自印度"
else "来自其他州"
end
from authors order by state
7 transaction
begin tran [tranname]
commit [tran] [tranname]
rollback [tran] [tranname]
seve tran [savepointname]
for example:
begin transaction exampletrans
save tansaction percentchanged
rollback transaction percentchanged
commit tansaction
