1.while语法
while 布尔表达式
{sql语句或语句块}
break --跳出本层循环
{sql语句或语句块}
continue --跳出本次循环
{sql语句或语句块}
2.while实例
样例数据
要求：如果3-15号的平均分小于85，则将3-15号没人加5分，如果3-15号的最高分超过100分跳出循环。
语句：
while (select avg([score]) from [Table_1] where id between 3 and 15)<85
begin
update [Table_1]
set score=score+5
where id between 3 and 15
if (select max(score) from [Table_1] where id between 3 and 15)>=100
break
end
执行结果：select * from [Table_1]
