SQL Statement Count NULL Values

[Chad S]

Hello,

Thanks for helping me with this... I really appreciate it.

I have a table called tblPatientDemog raphics with a number of columns.
I would like to count the number of NULL values per record within my
table.

tblPatientDemog raphics
PatientID Age Weight Height Race
1234567 20 155 <NULL> Caucasian
8912345 21 <NULL> <NULL> <NULL>

In the first example above I want to display '1'
In the second example above I want to display '3'

Any help would be very much appreciated.

Thanks !

Chad

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[David Portas]

Re: SQL Statement Count NULL Values

Here are two possibilities:

SELECT
CASE WHEN patientid IS NULL THEN 1 ELSE 0 END+
CASE WHEN age IS NULL THEN 1 ELSE 0 END+
CASE WHEN weight IS NULL THEN 1 ELSE 0 END+
CASE WHEN height IS NULL THEN 1 ELSE 0 END+
CASE WHEN race IS NULL THEN 1 ELSE 0 END
FROM tblPatientDemog raphics

SELECT 5-COUNT(patientid )-COUNT(age)-COUNT(weight)-COUNT(height)-COUNT(race)
FROM tblPatientDemog raphics
GROUP BY <primary key column(s)>

--
David Portas
SQL Server MVP
--

[Chad S]

Re: SQL Statement Count NULL Values

Hello,

Thanks for your two suggestions. But is there a way to count the NULL
values using * ? Count(*) WHERE IS NULL ? I want to avoid listing out
each column name because there is probably about 20 or so columns in
that table.

Thanks,

Chad

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[David Portas]

Re: SQL Statement Count NULL Values

There isn't a way to do it without listing the columns unless you resort to
dynamic SQL. For reasons of reliability and ease of maintenance it's
generally a good idea to list columns by name in a query. Avoid using SELECT
* in production code. Query Analyzer lets you drag a list of column names
from the Object Browser into the query window, which can save some typing
effort.

--
David Portas
SQL Server MVP
--