Button Selection Syntax

[rebelfox]

I have a field in a table that can contain NULL, Blanks or a unique value.

I would like to have a button on my sheet that will enable me to select all rows with a value of NULL or blanks.

To make NULL selectable I have used a line on the LOAD statement to convert NULL to ‘None’.

MyTable1:
OUTER JOIN LOAD

      MyField1,

      MyField2,

      MyField3
    IF(ISNULL(MyField4),'None',MyField4) As My_Code
RESIDENT MyTable2;

If I add a Listbox for MY_Code I get to many possible values and would like to select with typing in ‘N’

to reduce the list before selecting ‘None’.
How do I code the button to select ‘None’?

I see the Button is a sheet object that can be added with an Action of ‘Select In field’ but I don’t understand the syntax. 
There is a ‘field’ box which presumably needs to be MyCode.

How do you then code the condition in ‘Search String’?.

[marcus_sommer]

Before you think on selection-actions you should make sure that your data are proper. You write that you used an outer join and that you have to many possible values - that sounds that the datamodel don't worked properly.

- Marcus

[simenkg]

If you are just selecting one value then you simply write it directly

Field: My_Code

Value: None

If you are selecting multiple values then the syntax is

(Value1|Value2|Value3)

[Digvijay_Singh]

Do you want something like this?

[Gabriel]

Hi,

My advice is to convert the NULL values to something select-able.

Have this code before  MyTable1:

Map_Nulls:
Mapping LOAD
NULL(),
‘<Unknown>’
AutoGenerate 1;

And this after   MyTable1:

MAP FieldName, * using Map_Nulls;

[rebelfox]

That was my original thoughts yes.

[rebelfox]

Gets me half way there.

Field:My_Code

Value:None

Definitely works.

I can't get the multiple values to work though.