Se l'idea è di ottenere un risultato qualcosa del genere:
col emp
------ ------
FName 15
LName 2
Age 22
..usa:
SELECT 'FName' AS col, SUM(CASE FName IS NULL || FName='' THEN 1 ELSE 0 END) as emp FROM MyTable
UNION
SELECT 'LName' AS col, SUM(CASE LName IS NULL || LName='' THEN 1 ELSE 0 END) as emp FROM MyTable
UNION
SELECT 'Age' AS col, SUM(CASE Age IS NULL || Age='' THEN 1 ELSE 0 END) as emp FROM MyTable
...oppure:
SELECT SUM(CASE t.fname IS NULL OR t.fname = '' THEN 1 ELSE 0 END) AS fname_count,
SUM(CASE t.lname IS NULL OR t.lname = '' THEN 1 ELSE 0 END) AS lname_count,
SUM(CASE t.age IS NULL OR t.age = '' THEN 1 ELSE 0 END) AS age_count
FROM MYTABLE t
