Counting every row where certain column is not null or empty

Question

I am trying to get a COUNT where a certain column should have at least a value. If this column has EMPTY or NULL value, this should not be included in the COUNT . The problem is, I've tried many different SQL functions (eg: IS NOT NULL , <> , LTRIM , RTRIM , etc...) but rows that don't have values are still included in the count.

For example; in the database I have a column called MYDESCRIPTION . There are four records in the table. Two of them have a value in the MYDESCRIPTION column, two of them don't. When I look for a count for those that have a value, the other two that don't have are still included in the result. So it is still showing four.

Here are some sample queries within a specific day:

SELECT COUNT(*)
FROM TABLE
WHERE DATE (CREATIONDATE) >= '2014-12-01' AND
DATE (CREATIONDATE) <= '2014-12-01' AND
MYDESCRIPTION <> ''

And

SELECT COUNT(*)
FROM TABLE
WHERE DATE (CREATIONDATE) >= '2014-12-01' AND
      DATE (CREATIONDATE) <= '2014-12-01' AND 
      MYDESCRIPTION IS NOT NULL

These two simple queries are just some that I have tried. I suppose the query is still counting the column that has no value as it seems like it has a value.

Answer 1

Your WHERE clause should most likely look like:

WHERE DATE (CREATIONDATE) = '2014-12-01'  
  AND MYDESCRIPTION IS NOT NULL
  AND MYDESCRIPTION <> ''

Answer 2

SELECT COUNT(*) FROM TABLE  
WHERE DATE (CREATIONDATE) >= '2014-12-01' 
AND  DATE (CREATIONDATE) <= '2014-12-01' 
AND (MYDESCRIPTION IS NOT NULL and MYDESCRIPTION <> '')

Answer 3

You can use SUM(CASE...) for situations like this. Adjust the syntax as needed for your DBMS.

SELECT 
      SUM(CASE WHEN LENGTH(MYDESCRIPTION) = 0 THEN 0 ELSE 1) END) AS "Non-Nulls"
FROM TABLE
WHERE DATE (CREATIONDATE) >= '2014-12-01' AND
      DATE (CREATIONDATE) <= '2014-12-01' AND 
      MYDESCRIPTION IS NOT NULL

Answer 4

Try this:

SELECT COUNT (*)
FROM
(SELECT * FROM TABLE
WHERE 1=1
AND (CAST (CREATIONDATE AS DATE) BETWEEN CAST('2014-12-01' AS DATE) AND CAST('2014-12-01' AS DATE) )
AND (MYDESCRIPTION IS NOT NULL AND LENGTH(TRIM(MYDESCRIPTION)) > 0 )
)

Answer 5

SELECT COUNT(*) FROM TABLE
WHERE DATE (CREATIONDATE) >= '2014-12-01'
AND DATE (CREATIONDATE) <= '2014-12-01'
AND (MYDESCRIPTION IS NOT NULL and RTRIM(MYDESCRIPTION) <> '')

IS NOT NULL is a different condition from <> '' .

IS NOT NULL means the value is unknown.

<> '' means the value is not equal to a ZLS, or Zero Length String.

In adding the RTRIM , I was eliminating the possibility of a CHAR or NCHAR field that was equal to a bunch of spaces, which may or may not be desirable in this OP's question.