PostgreSQL/Select Query/Row

Cast row function

postgres=#
postgres=# CREATE FUNCTION getf1(mytable) RETURNS int
postgres-# AS "SELECT $1.f1"
postgres-# LANGUAGE SQL;
CREATE FUNCTION
postgres=#
postgres=# CREATE TYPE myrowtype AS (f1 int, f2 text, f3 numeric);
CREATE TYPE
postgres=#
postgres=# CREATE FUNCTION getf1(myrowtype) RETURNS int
postgres-# AS "SELECT $1.f1"
postgres-# LANGUAGE SQL;
CREATE FUNCTION
postgres=#
postgres=# SELECT getf1(ROW(1,2.5,"this is a test")::mytable);
 getf1
-------
     1
(1 row)
postgres=#
postgres=# SELECT getf1(CAST(ROW(11,"this is a test",2.5) AS myrowtype));
 getf1
-------
    11
(1 row)
postgres=#
postgres=# drop function getf1(myrowtype);
DROP FUNCTION
postgres=# drop type myrowtype;
DROP TYPE
postgres=# drop table mytable cascade;
NOTICE:  drop cascades to function getf1(mytable)
DROP TABLE
postgres=#
postgres=#

Pass "row" function to function

postgres=#
postgres=#
postgres=# CREATE TABLE mytable(f1 int, f2 float, f3 text);
CREATE TABLE
postgres=#
postgres=# CREATE FUNCTION getf1(mytable) RETURNS int AS "SELECT $1.f1" LANGUAGE SQL;
CREATE FUNCTION
postgres=#
postgres=# -- No cast needed since only one getf1() exists
postgres=# SELECT getf1(ROW(1,2.5,"this is a test"));
 getf1
-------
     1
(1 row)
postgres=#
postgres=#
postgres=# drop function getf1(mytable);
DROP FUNCTION
postgres=# drop table mytable;
DROP TABLE
postgres=#
postgres=#
postgres=#

Row Constructors

postgres=# -- Row Constructors
postgres=#
postgres=# SELECT ROW(1,2.5,"this is a test");
           row
--------------------------
 (1,2.5,"this is a test")
(1 row)
postgres=#
postgres=#

Using "Row" function in a function

postgres=#
postgres=# CREATE TABLE emp (
postgres(#    name        text,
postgres(#    salary      numeric,
postgres(#    age         integer,
postgres(#    cubicle     point
postgres(# );
CREATE TABLE
postgres=#
postgres=# insert into emp values ("None", 1000.0, 25, "(2,2)");
INSERT 0 1
postgres=#
postgres=#
postgres=# CREATE FUNCTION new_emp() RETURNS emp AS $$
postgres$#    SELECT ROW("None", 1000.0, 25, "(2,2)")::emp;
postgres$# $$ LANGUAGE SQL;
CREATE FUNCTION
postgres=#
postgres=# SELECT (new_emp()).name;
REATE
 name
------
 None
(1 row)
postgres=#
postgres=# drop function new_emp();
DROP FUNCTION
postgres=# drop table emp;
DROP TABLE
postgres=#
postgres=#