Count number of NULL values in each column in SQL - sql

Question

I am trying to write a script that will show the number of non-null values in each column as well as the total number of rows in the table.
I have found a couple ways to do this:
SELECT sum(case my_column when null then 1 else 0) "Null Values",
sum(case my_column when null then 0 else 1) "Non-Null Values"
FROM my_table;
and
SELECT count(*) FROM my_table WHERE my_column IS NULL
UNION ALL
SELECT count(*) FROM my_table WHERE my_column IS NOT NULL
But these require me to type in each column name manually. Is there a way to perform this action for each column without listing them?

Answer 1

You should use execute:
DECLARE #t nvarchar(max)
SET #t = N'SELECT '
SELECT #t = #t + 'sum(case when ' + c.name + ' is null then 1 else 0 end) "Null Values for ' + c.name + '",
sum(case when ' + c.name + ' is null then 0 else 1 end) "Non-Null Values for ' + c.name + '",'
FROM sys.columns c
WHERE c.object_id = object_id('my_table');
SET #t = SUBSTRING(#t, 1, LEN(#t) - 1) + ' FROM my_table;'
EXEC sp_executesql #t

Answer 2

As Paolo said, but here is an example:
DECLARE #TableName VARCHAR(512) = 'invoiceTbl';
DECLARE #SQL VARCHAR(1024);
WITH SQLText AS (
SELECT
ROW_NUMBER() OVER (ORDER BY c.Name) AS RowNum,
'SELECT ''' + c.name + ''', SUM(CASE WHEN ' + c.Name + ' IS NULL THEN 1 ELSE 0 END) AS NullValues FROM ' + #TableName AS SQLRow
FROM
sys.tables t
INNER JOIN sys.columns c ON c.object_id = t.object_id
WHERE
t.name = #TableName),
Recur AS (
SELECT
RowNum,
CONVERT(VARCHAR(MAX), SQLRow) AS SQLRow
FROM
SQLText
WHERE
RowNum = 1
UNION ALL
SELECT
t.RowNum,
CONVERT(VARCHAR(MAX), r.SQLRow + ' UNION ALL ' + t.SQLRow)
FROM
SQLText t
INNER JOIN Recur r ON t.RowNum = r.RowNum + 1
)
SELECT #SQL = SQLRow FROM Recur WHERE RowNum = (SELECT MAX(RowNum) FROM Recur);
EXEC(#SQL);

Answer 3

may be this works
select count(case when Column1 is null then 1 end) as Column1NullCount,
count(case when Column2 is null then 1 end) as Column2NullCount,
count(case when Column3 is null then 1 end) as Column3NullCount
...
from My_Table

Answer 4

you can go with dynamic sql and sys tables.
depending on the version of sql you are using the syntax will change slightly but these are the steps:
- list the columns reading sys.columns and save the list in a temp table or table variable
- make a loop through that temp table and build the sql using the same logic you would apply manually
- execute the dynamic sql built on previous step with sp_executesql