Oracle,sql server的空值(null)判断

sql server

替换null:isnull(arg,value)

如:select isnull(price,0.0) from orders ,如果price为null的话，用0.0替换

与null比较: is not null，is null

如 select * from orders where price is null ,price等于null

如: select * from orders where price is not null ,price不等于null


Oracle

替换null: nvl(arg,value)

如: select nvl(price,0.0) form orders

与null比较: is not null，is null

如 select * from orders where price is null ,price等于null

如: select * from orders where price is not null ,price不等于null