I have a data source (from an imported Access query) where each row has a value 'pass' or 'fail' in a column named pf. This pass/fail evaluation is based on the existence of some values across multiple columns (non-numeric, mostly evaluating for existence of "NO" in question columns). I want to use the count of the rows with either value to get the number sampled and number of samples which have passed. How do I write an expression which uses this "conditional count" to return the passing rate (percentage). So, the plain English formula for this would be:
(Count of rows with 'pass' in pf field)/(Count of rows with 'pass' + Count of rows with 'fail' in pf field)
Some rows may have a null value in the pf field so I want to discount these entirely (though this could be selected out at a higher level in the underlying query, I believe).