How can define a value mapping for when it shows any last value

I want define value mapping .
first value mapping I have create Null and shows log file is ok
now I need to define other value mapping that if I have any value instead of Null it shows Fail . I think I have to define regex . But would you please say how can set regex parameter that if I had last values it shows error ?

Would you please help me about it ?

This should work:

Please note that it only works with string fields. You can use the convert field type transformation to make the field a string if needed: Transform data | Grafana documentation

For future reference, here is the go regex syntax: syntax package - regexp/syntax - Go Packages

1- Does it your mean when set such as your pic it will show fail when returned any string ?
2- How can set other value when it does not return anything display text = OK

My output is : exported “INTERNATIONAL”.“ERROR_MESSAGE” 14.35 KB 170 rows
and I set value map such as attached pic but now it is showing Log file is OK

Can anyone help me about it ?

Would you please help me about it ?