Thread: PL/pgSQL Copy data from one table to another

Hey Guys,

I am trying to copy data from one table to another using plpgsql. The two
tables have different structure cause the new one is object-table. My
function is this :

CREATE OR REPLACE FUNCTION copy_customers() RETURNS integer as $BODY$
DECLARE
     idcounter integer := 1;
     firstname text;
     lastname text;
     address1 text;
     address2 text;
     city text;
     state text;
     zip text;
     country text;
     region text;
BEGIN
FOR idcounter In 1..20000
LOOP

        -- Add the values into the variables.
    SELECT
"FirstName","LastName","Address1","Address2","City","State","Zip","Country","Region"
    INTO firstname, lastname,address1,address2,city,state,zip,country,region
    FROM "Customers"
    WHERE "CustomerId" = idcounter;

        --Insert the variables to the new table.
    INSERT INTO "Customers_object_table" (customerid , firstname, lastname,
address)
VALUES(idcounter,firstname,lastname,(address1,address2,city,state,zip,country,region));
END Loop;

return 1;
END;
$BODY$
LANGUAGE plpgsql;


This function is working fine, but the problem is that the table "Customers"
has more than 20 columns, so the code is ugly and unmaintainable. Also I
want to do the same job for 10 more tables.

Can somebody help me to change this function in a way that I won't have to
declare the columns?

Notice that the destination-tables are object tables and can be different
than the old tables, so I am not sure if what I ask is possible.

Kind Regards,
George Ant



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On Wed, Feb 5, 2014 at 7:53 AM, George Ant <g.antonopoulos000@gmail.com> wrote:

Hey Guys,

I am trying to copy data from one table to another using plpgsql. The two
tables have different structure cause the new one is object-table. My
function is this :

CREATE OR REPLACE FUNCTION copy_customers() RETURNS integer as $BODY$
DECLARE
     idcounter integer := 1;
     firstname text;
     lastname text;
     address1 text;
     address2 text;
     city text;
     state text;
     zip text;
     country text;
     region text;
BEGIN
FOR idcounter In 1..20000
LOOP

        -- Add the values into the variables.
        SELECT
"FirstName","LastName","Address1","Address2","City","State","Zip","Country","Region"
        INTO firstname, lastname,address1,address2,city,state,zip,country,region
        FROM "Customers"
        WHERE "CustomerId" = idcounter;

        --Insert the variables to the new table.
        INSERT INTO "Customers_object_table" (customerid , firstname, lastname,
address)
VALUES(idcounter,firstname,lastname,(address1,address2,city,state,zip,country,region));
END Loop;

return 1;
END;
$BODY$
LANGUAGE plpgsql;


This function is working fine, but the problem is that the table "Customers"
has more than 20 columns, so the code is ugly and unmaintainable. Also I
want to do the same job for 10 more tables.

Can somebody help me to change this function in a way that I won't have to
declare the columns?

Notice that the destination-tables are object tables and can be different
than the old tables, so I am not sure if what I ask is possible.

Kind Regards,
George Ant



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I assume you created a composite type (addresstype) in Customers_object_table.

CREATE OR REPLACE FUNCTION copy_customers() RETURNS integer as $BODY$
BEGIN

    INSERT INTO Customers_object_table (customerid, firstname, lastname, address)
    SELECT c.customerid, c.firstname, c.lastname, (c.address1, c.address2, c.city, c.zip, c.country, c.region)::addresstype
    FROM Customers c
    WHERE c.customerid >= 1 AND c.customerid <= 20000;

    RETURN 1;
END
$BODY$

LANGUAGE plpgsql;

Hey Guys,

Thank you for your replies! Your suggestions worked fine!! :) Also my code
looks a lot cleaner now!

Kind Regards,
George Ant.



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George Ant wrote
> Hey Guys,
>
> Thank you for your replies! Your suggestions worked fine!! :) Also my code
> looks a lot cleaner now!
>
> Kind Regards,
> George Ant.

Have you considered just creating a view, or even retrieval functions, the
generate these "object forms" on the fly instead of altering your database
schema?  Using arrays for master-detail relationships is typically
considered wrong and is definitely non-relational.  Your application should
not dictate schema design to this level generally but instead you should add
an O-R layer where needed.

David J.








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