PostgreSQL可用ARRAY来替代Oracle中的collection type,包括associative array/Varrays (Variable-Size Arrays)/Nested Tables

Oracle
简单举个例子:

drop table if exists employee;create table employee(id int,name varchar(30),department varchar(30),salary float);insert into employee(id,name,department,salary) select rownum,substrb(object_name,1,30),substrb(object_name,1,30),1000 from dba_objects;DECLARE TYPE EmpTabTyp IS TABLE OF employee%ROWTYPE INDEX BY PLS_INTEGER; emp_tab EmpTabTyp; i int := 0;BEGIN /* Retrieve employee record. */ for c1 in (select * from employee) loop emp_tab(i).id := c1.id; emp_tab(i).name := c1.name; emp_tab(i).department := c1.department; emp_tab(i).salary := c1.salary; i := i+1; end loop; -- SELECT * INTO emp_tab(100) FROM employee WHERE id = 100;END;/

更简单的做法是使用bulk collection

DECLARE TYPE EmpTabTyp IS TABLE OF employee%ROWTYPE INDEX BY PLS_INTEGER; emp_tab EmpTabTyp; i int := 0;BEGIN /* Retrieve employee record. */ select id,name,department,salary bulk collect into emp_tab from employee;END;/

PostgreSQL
使用ARRAY

drop type record_of_employee;CREATE TYPE record_of_employee AS (id int,name varchar(30),department varchar(30),salary float);do$$declare employees record_of_employee[];begin select array_agg(employee) into employees from employee limit 1; raise notice 'id is %',employees[1].id; raise notice 'name is %',employees[1].name;end$$;

对于Associative array indexed by string,PG的数组则替代不了.

DECLARE -- Associative array indexed by string: TYPE population IS TABLE OF NUMBER -- Associative array type INDEX BY VARCHAR2(64); -- indexed by string...

参考资料
PL/SQL Collections and Records
Oracle PL/SQL Collections: Varrays, Nested & Index by Tables
Collections in Oracle PL/SQL
Working with Collections
Take a Dip into PostgreSQL Arrays