PostgreSQL Server Programming - Second Edition

Passing composite-type arguments

A composite-type, such as a table, or a user-defined type is passed to the PL/Tcl function as an associative array (Hash table). The attribute names of the composite-type are the element names in the array. Attributes with NULL values are not available in the Tcl array.

Let's take a look at an arbitrary example. We will create a function that takes a composite type as an argument and does some calculations based on the attribute values of the type. Let's create our type and the function:

CREATE TABLE orders(orderid int, num_people integer, order_amount decimal); INSERT INTO orders VALUES(1,1,23); INSERT INTO orders VALUES(2,3,157); INSERT INTO orders VALUES(3,5,567.25); INSERT INTO orders VALUES(4,1,100); CREATE ...