Help me with Custom Column template

Dear you guys,

I have set up a column #readby (text), which stores the 'read' info of more than one person, say: NQK (2016-09-12), NLT (2015-05-24), An (2014)

Now I created another composite column to read from this. What I want for this new column is to display only NQK (whatever_inside)

Please teach me the right template.