--if语句

declare @age int

select @age=DATEDIFF(year,stuBirthday,getdate()) from student where stuName='张飞'

if(@age>=18)

begin--begin...end必须有

   print N'已成年'

end

else

begin

print N'未成年'

end

 

--练习：计算全班同学英语平均分,如果是null，就当0分计

select AVG(math) from score

select * from score

 

declare @count int

declare @sum int

select @count=COUNT(1) from score

select  @sum=SUM(math) from score

declare @average float

set @average=@sum/@count

select @average

 

 

 

--while 语句

--练习：计算1-100之间所有奇数的和

declare @sum int

set @sum=0

declare @i int

set @i=1

while @i<=100

begin

  if(@i%2!=0)

  begin

  set @sum = @sum+@i

  end

  set @i=@i+1

end

select @i