Re: Count of non-null values per table column
От | David Nelson |
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Тема | Re: Count of non-null values per table column |
Дата | |
Msg-id | COL126-W3799A33B6369CDCDE76578F17C0@phx.gbl обсуждение исходный текст |
Ответ на | Count of non-null values per table column (David Nelson <dlnelson77808@outlook.com>) |
Ответы |
Re: Count of non-null values per table column
(John McKown <john.archie.mckown@gmail.com>)
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Список | pgsql-general |
Well it is certainly nice to see that my choice to send my question using plain text was honored by this email service. Apologiesfor 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>>From: dlnelson77808@outlook.com<br>> To: pgsql-general@postgresql.org<br>>Subject: [GENERAL] Count of non-null values per table column<br>> Date: Fri, 14 Aug2015 14:32:36 +0000<br>><br>> Hello list,<br><br>Apologies if this has been asked before. My searchonly turned up ways to list the total non-null values for all columns as a single number. I want the count for eachcolumn by column.<br><br>I have inherited a database consisting of two related huge monolithic tables thatlack referential integrity between them, or even basic data constraints. One of the problems these tables have is everysingle non-PK column is NULLable. I am trying to understand the information that is actually stored and used so thatI can implement a (hopefully) better design. Towards that end I would like to know the count of non-null values in eachcolumn per column. In other words I would like to get the following output from a table (the numbers are totally madeup):<br><br>column_name | num_values<br>------------+-----------<br>col1 | 5787<br>------------+-----------<br>col2 | 17<br>------------+-----------<br>col3 | 567<br>------------+-----------<br>col4 | 5787<br>------------+-----------<br>col5 | 143<br>------------+-----------<br>col6 | 1<br>------------+-----------<br>...<br><br>Isthis 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.<br><br>Thanks,<br>David<br>><br>> --<br>> Sent via pgsql-generalmailing list (pgsql-general@postgresql.org)<br>> To make changes to your subscription:<br>> http://www.postgresql.org/mailpref/pgsql-general<br>
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