Re: [GENERAL] Count of non-null values per table column

[David Nelson]

Well it is certainly nice to see that my choice to send my question using plain 
text was honored by this email service. Apologies for that mess. The output I 
am looking for is a series of rows with two columns, one the name of the table 
column, and the other the count of non-null values in a table's column of that 
same name, for all column names in the 
table.<br><br>Thanks<br><br>----------------------------------------<br>&gt; 
From: dlnelson77...@outlook.com<br>&gt; To: 
pgsql-general@postgresql.org<br>&gt; Subject: [GENERAL] Count of non-null 
values per table column<br>&gt; Date: Fri, 14 Aug 2015 14:32:36 
+0000<br>&gt;<br>&gt; Hello list,&lt;br&gt;&lt;br&gt;Apologies if this has been 
asked before. My search only turned up ways to list the total non-null values 
for all columns as a single number. I want the count for each column by 
column.&lt;br&gt;&lt;br&gt;I have inherited a database consisting of two 
related huge monolithic tables that lack referential integrity between them, or 
even basic data constraints. One of the problems these tables have is every 
single non-PK column is NULLable. I am trying to understand the information 
that is actually stored and used so that I can implement a (hopefully) better 
design. Towards that end I would like to know the count of non-null values in 
each column per column. In other words I would like to get the following output 
from a table (the numbers are totally made up):&lt;br&gt;&lt;br&gt;column_name 
| 
num_values&lt;br&gt;------------+-----------&lt;br&gt;col1&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;
 |&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp; 
5787&lt;br&gt;------------+-----------&lt;br&gt;col2&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;
 
|&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;
 
17&lt;br&gt;------------+-----------&lt;br&gt;col3&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;
 |&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp; 
567&lt;br&gt;------------+-----------&lt;br&gt;col4&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;
 |&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp; 
5787&lt;br&gt;------------+-----------&lt;br&gt;col5&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;
 |&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp; 
143&lt;br&gt;------------+-----------&lt;br&gt;col6&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;
 
|&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;&amp;nbsp;
 1&lt;br&gt;------------+-----------&lt;br&gt;...&lt;br&gt;&lt;br&gt;Is this 
possible through one or more of the system views, or will I need to write a 
function to do this? Obviously I can just issue multiple SELECT 
COUNT(column)... statements, but I'd rather 
not.&lt;br&gt;&lt;br&gt;Thanks,&lt;br&gt;David<br>&gt;<br>&gt; --<br>&gt; Sent 
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