简体   繁体   中英

Calculating blank fields in MS Access via a SQL query

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.

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>)

The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.

 
粤ICP备18138465号  © 2020-2024 STACKOOM.COM