通过SQL查询计算MS Access中的空白字段

Question

I have a table called 'DEMO'. Under the column 'SEX' I want to find out how many blank cells I have?

I have tried:

SELECT Count(SEX) AS CountIfSexNull FROM DEMO WHERE (((DEMO.SEX) Is Null));

however, get a result of 0.

When I use 'Query Design' to select the column 'SEX' and manually filter for blanks I get the value of 2.

The query works fine on numerical fields, ie AGE and I get a correct answer except instead of 'Is Null' I use '0' ie

SELECT COUNT(DEMO_AGE) AS CountIfAgeNull FROM DEMO WHERE (DEMO.DEMO_AGE = 0);

I'm using MS Access 2010 with a .accdb database.

Answer 1

COUNT [Fieldname] does not count nulls, either use an ID or *, for example:

SELECT Count(*) AS CountIfSexNull
FROM DEMO
WHERE DEMO.SEX Is Null

Reference: In SQL is there a difference between count(*) and count(<fieldname>)