如何在 Access 查询中检查变量是否为空并为其分配值（如果是）？

Question

I'm not a big Access user, but I need to work with it from time to time. Now I have run into a, for me, completely new task with Access. I can solve this type of problem with SQL in MS SQL Server. But the SQL syntax in Access doesn't recognise my SQL code at all so I guess it's quite different from "regular" SQL.

Anyway, I have a table that needs to be sorted over some attributes. For this question we can take two and call them A1 and A2 . A1 doesn't have any null values, A2 does. The sort order is on A2 :

• If A2 has a value, sort by it.
• If A2 is null, then sort by the value from A1 .

I have tried so many different ways to solve this and all of them has failed. It's absolutely clear that my knowledge in Access is limited so I guess that I'm approaching this in a faulty way.

Answer 1

Use NZ() :

ORDER BY NZ(A2, A1)

NZ returns the second parameter if the first is null, otherwise it returns the first parameter.