6 过滤数据：where

过滤数据：where

selete p_price,p_name

from product

where p_price=2.50;

注意：同时使用order by和where时，order by 位于where之后

where的操作符：=,!=,<>,<=,>=.<,>,between

范围检查：包括边界值

between 5 and 10;

空值检查：

selete p_name

from product

where p_price is null;