From: christian.michels@eifelgeist.com
To: pgsql-sql@postgresql.org
Subject: executing dynamic commands
Date: Wed, 01 Feb 2006 16:26:16 +0100
Message-ID: <15802822.125111138807576371.JavaMail.servlet@kundenserver> (raw)
Hi,
I user PostgreSQl 8.0.4 on Win2003 Server and write a function to copy rows from one table into another table with the same column definition.
My first approach was to use something like:
query_value := 'INSERT INTO ' || tabledest || ' SELECT * FROM ' || tablesrc;
EXECUTE query_value;
This only works if the column definition AND the order between source and destination is the same !
In my case I have always the same column definitions but they are not in the same order between source and destination table.
What I tryed then is to loop through the column definition of the source and query the sourcetable for the value. For that I have to execut a query with dynamic tablename and dynamic columname to generate two stings one with the columndefinitin and one with the columnvalues to exececute something like: INSERT INTO tabelfoo (columndefinitinstring) VALUES (columnvaluesstring)
see snip of function:
fieldvalues RECORD;
output RECORD;
insertvalues VARCHAR;
fieldname VARCHAR;
-- Get Attribute List from Table and write it to output
-- Read Values of Fieldname from source
query_value := 'select * from ' || tablesrc ;
FOR fieldvalues IN EXECUTE query_value LOOP
FOR output IN SELECT a.attnum,
a.attname AS field,
FROM
pg_class c, pg_attribute a, pg_type t
WHERE
c.relname = tablesrc AND
a.attnum > 0 AND
a.attrelid = c.oid AND
a.atttypid = t.oid
ORDER BY a.attnum LOOP
-- Read Field Name from Out Table
fieldname := output.field;
-- Write Field Name into Variable
IF insertcolumns IS NULL THEN
insertcolumns := fieldname;
ELSE
insertcolumns := insertcolumns || ',' || fieldname;
END IF;
Until here everyting is fine ... but now I try to query the value from RECORD fieldvalues with the columname fieldname variable from the inner loop !
I tryed the following ...
query_value := 'select quote_ident(' || fieldvalues || ').quote_literal(' || fieldname ||')';
EXECUTE query_value;
and I get the following error message ...
ERROR: could not find array type for data type record
CONTEXT: SQL statement "SELECT 'select quote_ident(' || $1 || ').quote_literal(' || $2 ||')'"
PL/pgSQL function "prx_db__appendtable" line 87 at assignment
END LOOP;
END LOOP;
I know the function is not runnable, but my question is how can I dynamically combine "fieldvalues"."fieldname" to read the values column by colum out if a RECORD variable to generate the "columnvaluesstring" mentioned above ?!
Maybe this approach is to complicated and there is a quick and easy solution ?!
Any help is very much appreciated !!
Thanx a lot & Regards
Chris
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To: pgsql-sql@postgresql.org
Cc: christian.michels@eifelgeist.com
Subject: Re: executing dynamic commands
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