Using CASE Statement with two strings in QGIS

Question

I am trying to fill out a field based on information in a different field in the same layer using a CASE Statement in the Field Calculator. My table structure looks like this:

SPECIES	SHORT
Toad	NULL
NULL	B
Fish	NULL
Plant	NULL

My goal looks like this:

SPECIES	SHORT
Toad	T
NULL	B
Fish	F
Plant	P

The Expression I am using and does not work looks like this:

CASE  
   WHEN "Species" LIKE 'Toad' THEN 'T'  
   WHEN "Species" LIKE 'Fish' THEN 'F'  
   WHEN "Species" LIKE 'Plant' THEN 'P'  
END

The result is that everything in "SHORT" ends up being NULL.

The Field "SPECIES" is a VALUE MAP widget type. "SHORT" is a TEXT EDIT. I am using QGIS 3.1

Answer 1

To get the same result you can use even a simpler formula with left() to get the first letter only.

left("SPECIES", 1) 

Answer 2

using wildcards % like '%Toad%' worked for me.

My Expression now looks like this:

CASE  
   WHEN "SPECIES" LIKE '%Toad%' THEN 'T'  
   WHEN "SPECIES" LIKE '%Fish%' THEN 'F'  
   WHEN "SPECIES" LIKE '%Plant%' THEN 'P'  
   ELSE "SHORT"
END  

I added the ELSE "SHORT" to prevent attributes to be lost if "SPECIES" is NULL