Count not null in sql

Question

I have a table A with column data:

mdr1222
-------
pprgd24
-------
invalid
-------
invalid
abc2345

I want to get a count of the invalid and blank(---). I tried :

SELECT count(data)
from A
where data = 'invalid' and  null

but it doesn't work. Can someone please help me figure out what I am doing wrong here?

Answer 1

This should work as well.

SUM(CASE WHEN data IS NULL OR data = 'Invalid' THEN 1 ELSE 0 END)
FROM A

Answer 2

select count(column_name) from table_name where column_name is not null

returns number of rows where column_name value is not null

select count(column_name) from table_name where column_name is null

returns number of rows where column_name value is null