我想知道Access中有没有类似于Sql Server中的isnull函数，就是说如果这个值为空，就可以给它赋一个值，例如isnull(username,'guest')就是说如果username字段为空，则返回值'guest',access中有isnull函数，但只是判断是否为空，不能用。

Learn the differences between Is Null and IsNull() in Access Your email has been sent How many null values exist? What is the difference between a null value and a blank entry? This article answers ...

I've been in an argument with one of our devs that took an update statement with an inner join and made it a left join (because inner was missing some records somehow in the left table - tableB in ...