Re: returning the number of rows output by a copy command from a function

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От Misa Simic
Тема Re: returning the number of rows output by a copy command from a function
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Msg-id CAH3i69nm14X9O1+765De+9gHNnweNE947XR4kswhKBhowwLwRw@mail.gmail.com
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Ответ на returning the number of rows output by a copy command from a function  (James Sharrett <jsharrett@tidemark.net>)
Список pgsql-sql
Hi

Maybe:


1.

strSQL := 'copy (select MyColumns from MyExportTable) to MyFile.csv with CSV HEADER;';
Execute strSQL

strSQL := 'Select count(*) from (select MyColumns from MyExportTable) t';
Execute strSQL into export_count;

Return export_count;


Kind Regards,

Misa

On Wednesday, January 16, 2013, James Sharrett wrote:
I have a function that generates a table of records and then a SQL statement that does a COPY into a text file.  I want to return the number of records output into the text file from my function.  The number of rows in the table is not necessarily the number of rows in the file due to summarization of data in the table on the way out.  Here is a very shortened version of what I'm doing:


CREATE OR REPLACE FUNCTION export_data(list of parameters)
  RETURNS integer AS
$BODY$

declare
My variables

Begin

 { A lot of SQL to build and populate the table of records to export}


strSQL := 'copy (select MyColumns from MyExportTable) to MyFile.csv with CSV HEADER;';
Execute strSQL;

Return 0;

end
$BODY$
  LANGUAGE plpgsql VOLATILE

strSQL gets dynamically generated so it's not a static statement.

This all works exactly as I want.  But when I try to get the row count back out I cannot get it.  I've tried the following:

1.
strSQL := 'copy (select MyColumns from MyExportTable) to MyFile.csv with CSV HEADER;';
Execute strSQL into export_count;

Return export_count;

This give me an error saying that I've tried to use the INTO statement with a command that doesn't return data.


2.
strSQL := 'copy (select MyColumns from MyExportTable) to MyFile.csv with CSV HEADER;';
Execute strSQL;

Get diagnostics export_count = row_count;

This always returns zero.

3.
strSQL := 'copy (select MyColumns from MyExportTable) to MyFile.csv with CSV HEADER;';
Execute strSQL;

Return row_count;

This returns a null.

Any way to do this?


Thanks in advance,
James

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