流程控制
begin ……end将一个语句块包含起来，中间可以写任何语句
格式：
begin--开始
select *from student
end--结束
if
declare @bianliang int
set @bianliang = 10
if @bianliang>10 print ‘你好‘
else print ‘hello‘
若if后面有多个语句，用begin end作为分隔点
declare @shuxue decimal(18,2)
select @shuxue = MAX(shuxue) from fenshu
declare @stuid int
select @stuid = code from fenshu where shuxue = @shuxue
---select *from student where code = @stuid
declare @sex varchar(20)
select @sex = sex from student where code = @stuid
if @sex = ‘男‘
print‘这是男同学‘
else
print‘这是女同学‘
while
declare @shuxue int
set @shuxue = 75
while @shuxue<80
begin
print‘很好‘
set @shuxue = @shuxue+1
if @shuxue = 79
break
print ‘ok‘
end
declare @shuxue int
set @shuxue = 80
while @shuxue<95
begin
print‘很好‘+cast(@shuxue as varchar(10))
set @shuxue = @shuxue+1
if @shuxue = 93
break
if @shuxue>85 and @shuxue<90
begin
continue
end
print ‘ok‘
end
