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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 |