PostgreSQL/Subquery/Subquery Case

Using case expressions with sub-queries

   <source lang="sql">

postgres=# postgres=# postgres=# create table job( postgres(# ID int, postgres(# title varchar (10)); CREATE TABLE postgres=# postgres=# postgres=# insert into job(ID, title) values(1,"Developer"); INSERT 0 1 postgres=# insert into job(ID, title) values(2,"Tester"); INSERT 0 1 postgres=# insert into job(ID, title) values(3,"Designer"); INSERT 0 1 postgres=# insert into job(ID, title) values(4,"Programmer"); INSERT 0 1 postgres=# postgres=# select * from job;

id |   title

---

+------------

 1 | Developer
 2 | Tester
 3 | Designer
 4 | Programmer

(4 rows) postgres=# postgres=# CREATE TABLE employee ( postgres(# ID int, postgres(# name varchar(10), postgres(# salary real, postgres(# start_date date, postgres(# city varchar(10), postgres(# region char(1) postgres(# ); CREATE TABLE postgres=# postgres=# insert into employee (ID, name, salary, start_date, city, region) postgres-# values (1, "Jason", 40420, "02/01/94", "New York", "W"); INSERT 0 1 postgres=# insert into employee (ID, name, salary, start_date, city, region) postgres-# values (2, "Robert",14420, "01/02/95", "Vancouver","N"); INSERT 0 1 postgres=# insert into employee (ID, name, salary, start_date, city, region) postgres-# values (3, "Celia", 24020, "12/03/96", "Toronto", "W"); INSERT 0 1 postgres=# insert into employee (ID, name, salary, start_date, city, region) postgres-# values (4, "Linda", 40620, "11/04/97", "New York", "N"); INSERT 0 1 postgres=# insert into employee (ID, name, salary, start_date, city, region) postgres-# values (5, "David", 80026, "10/05/98", "Vancouver","W"); INSERT 0 1 postgres=# insert into employee (ID, name, salary, start_date, city, region) postgres-# values (6, "James", 70060, "09/06/99", "Toronto", "N"); INSERT 0 1 postgres=# insert into employee (ID, name, salary, start_date, city, region) postgres-# values (7, "Alison",90620, "08/07/00", "New York", "W"); INSERT 0 1 postgres=# insert into employee (ID, name, salary, start_date, city, region) postgres-# values (8, "Chris", 26020, "07/08/01", "Vancouver","N"); INSERT 0 1 postgres=# insert into employee (ID, name, salary, start_date, city, region) postgres-# values (9, "Mary", 60020, "06/09/02", "Toronto", "W"); INSERT 0 1 postgres=# postgres=# select * from employee;

id |  name  | salary | start_date |   city    | region

---

+--------+--------+------------+-----------+--------

 1 | Jason  |  40420 | 1994-02-01 | New York  | W
 2 | Robert |  14420 | 1995-01-02 | Vancouver | N
 3 | Celia  |  24020 | 1996-12-03 | Toronto   | W
 4 | Linda  |  40620 | 1997-11-04 | New York  | N
 5 | David  |  80026 | 1998-10-05 | Vancouver | W
 6 | James  |  70060 | 1999-09-06 | Toronto   | N
 7 | Alison |  90620 | 2000-08-07 | New York  | W
 8 | Chris  |  26020 | 2001-07-08 | Vancouver | N
 9 | Mary   |  60020 | 2002-06-09 | Toronto   | W

(9 rows) postgres=# postgres=# --Using case expressions with sub-queries postgres=# postgres=# SELECT salary, postgres-# CASE WHEN salary > 2000 THEN "N/A - (Out of price range)" postgres-# ELSE (SELECT title FROM employee e JOIN job j postgres(# ON (e.id = j.id) postgres(# WHERE j.title = "developer") postgres-# END AS cost_range postgres-# FROM employee postgres-# ORDER BY salary ASC postgres-# LIMIT 8;

salary |         cost_range

---

+----------------------------

 14420 | N/A - (Out of price range)
 24020 | N/A - (Out of price range)
 26020 | N/A - (Out of price range)
 40420 | N/A - (Out of price range)
 40620 | N/A - (Out of price range)
 60020 | N/A - (Out of price range)
 70060 | N/A - (Out of price range)
 80026 | N/A - (Out of price range)

(8 rows) postgres=# postgres=# drop table job; DROP TABLE postgres=# drop table employee; DROP TABLE postgres=#

      </source>