表:product ( maker, model, type)
pc ( model, speed, ram, hd, cd, price)
laptop (model, speed, ram, hd, screen, price)
printer (model, color, type, price)
问题
当在laptop中插入一条记录时,检查该记录的model number已经存在于product表中了
pc ( model, speed, ram, hd, cd, price)
laptop (model, speed, ram, hd, screen, price)
printer (model, color, type, price)
问题
当在laptop中插入一条记录时,检查该记录的model number已经存在于product表中了
on laptop
for insert
as
begin
if exists(select 1
from inserted i,product a
left product a
on i.model = a.model
)
..................
end
on laptop
for insert
as
begin
if exists(select 1
from inserted i,product a
left join product a
on i.model = a.model
)
..................
end
create trigger triggername
on laptop
after insert
as
begin
if exists(select 1
from laptop a join product a
on a.model = b.model
)
begin
rollback
print '不能插入!'
end
end
嘿嘿,两个别名全是a