zf-about notification Announcements display issues

1 Announcement End date is more than the current time is not displayed on the notification announcement

2 The announcement of the unrestricted time is also to be shown on the notice announcement.

So I added the following code to the background implementation class

It is important to note that the first problem was solved by adding an and

When you want to solve a second problem, you need to use the OR

Then you need to enclose these 2 conditions in parentheses.

Between these 2 conditions write or

And I made a mistake. Date is not = NULL to write date is null this is OK

Null is to be judged here involves the difference between IS and =

The first where xx = ' null ', the value of the XX character Gencun is four characters of NULL,
The second where xx is null, XX field does not exist, this is the database of the judgment syntax,
The third where IsNull (xx), xx field does not exist, this is the interface development language judgment grammar

"=" can only judge the value

And "is" to determine whether it is null

zf-about notification Announcements display issues