Using Elseif Conditional Statement in QGIS Field Calculator?

Question

I am trying to write an ELSEIF conditional statement in QGIS Field Calculator (version 1.8.0). I have used an example I found online:

CASE WHEN val < 0 THEN 'negative'
 WHEN val = 0 THEN "neutral'
 ELSE 'positive'
END

I modified the statement as follows:

CASE WHEN "GRID_ID" = 1 THEN 'complete'
 ELSEIF "GRID_ID" = 2 THEN "in progress'
 ELSE 'not started'
END

This statement would not run, the Output preview stated Expression is invalid. The more info stated: Parser Error: syntax error, unexpected COLUMN_REF, expecting WHEN or ELSE or END

If anyone has had this error, what did you do to fix it?

Answer 1

You have a few problems in your modified statement.

• Inconsistent use of quotes around "in progress'
• You don't need quotes around column names.
• You're using an "ELSEIF" when it should be a "WHEN".

The following should resolve all three issues and works for me in 1.8.0:

CASE WHEN GRID_ID = 1 THEN 'complete'
 WHEN GRID_ID = 2 THEN 'in progress'
 ELSE 'not started'
END

• Nathan W: "You don't need quotes around column names." You don't but I would still recommend it as it will help the syntax highlighter mark that part as a column.
• GIS-Jonathan: @NathanW - the Syntax highlighter marks column names in red whether you use quotes or not, at least it does in my 1.8.0 install.
• Nathan W: It does indeed. That is pretty embarrassing, I should have known it does that as I wrote the highlighter ;)
• GIS-Jonathan: @NathanW - Understandable. I can barely remember what I wrote yesterday after all. ;-)