Real Name	:	SharingCode.NET User
Subject	:	A simple sub-query: subquery return one value
Description	:	A simple sub-query: subquery return one value
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=# postgres=# -- A simple sub-query postgres=# postgres=# SELECT name FROM employee WHERE id = (SELECT id FROM job where title = 'Developer'); name ------- Jason (1 row) postgres=# postgres=# postgres=# drop table employee; DROP TABLE postgres=# drop table job; DROP TABLE postgres=# postgres=#
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