How to show multiple case conditions calculated column in CE function

Hi folks

I have SQL script code need to transfer to CE function

the sample code is

select xx, xx, xx, xx,

(case when a.X1 = 'xx' then 'xxxxx'

        when a.S1 is null then ''

         when b.M is null then a.S1

          else a.S1|| ' - ' || b.M end) as CA_LV

from Table A as a

left outer join

Table B as b

You can see, in the calculated column

there are multiple "when...then" and "else" statement

I want know how can this be transferred to CE function

Is function CE_CALC() working for more than one "when...then" statement?

Can anyone convert the sample code to CE function?

Thanks