Dynamic pivot query using PostgreSQL 9.3

SELECT *
FROM   crosstab (
   'SELECT ProductNumber, ProductName, Salescountry, SalesQuantity
    FROM   product
    ORDER  BY 1'
, $$SELECT unnest('{US,UK,UAE1}'::varchar[])$$
  ) AS ct (
   "ProductNumber" varchar
 , "ProductName"   varchar
 , "US"   int
 , "UK"   int
 , "UAE1" int);

Detailed explanation:

• PostgreSQL Crosstab Query
• Pivot on Multiple Columns using Tablefunc

Completely dynamic query for varying number of distinct Salescountry?

• Dynamic alternative to pivot with CASE and GROUP BY

While it's a two step process, this method will create a pivot with dynamic columns, without the need to specify the result set and without creating temp tables.

First we define a function that creates a dynamically prepared statement:

CREATE OR REPLACE FUNCTION flowms.pivotcode_sql(
    tablename character varying,
    rowc character varying,
    colc character varying,
    cellc character varying,
    celldatatype character varying)
    RETURNS character varying
    LANGUAGE 'plpgsql'

    COST 100
    VOLATILE 
AS $BODY$

declare
    dynsql1 varchar;
    dynsql2 varchar;
    columnlist varchar;
begin
    -- 1. retrieve list of column names.
    dynsql1 = 'select string_agg(distinct ''"''||'||colc||'||''" '||celldatatype||''','','' order by ''"''||'||colc||'||''" '||celldatatype||''') from '||tablename||';';
    execute dynsql1 into columnlist;
    -- 2. set up the crosstab query
    --tablename = REPLACE(text, ''', E'\\"')
    dynsql2 = 'prepare crosstab_stmt as select * from crosstab (
 ''select '||rowc||','||colc||','||cellc||' from '||replace(tablename, chr(39),E'\'\'')||' group by 1,2 order by 1,2'',
 ''select distinct '||colc||' from '||replace(tablename, chr(39),E'\'\'')||' order by 1''
 )
 as newtable (
 '||rowc||' varchar,'||columnlist||'
 );';
    deallocate all;
    execute dynsql2;
    return dynsql2;
end

$BODY$;

You can now call the function

select pivotcode_sql('tablename', 'rowfield', 'columnfield', 'sum(value)', 'integer');

which will create the prepared statement. Next you can execute the prepared statement:

execute crosstab_stmt;