LEFT OUTER JOIN vs RIGHT OUTER JOIN
SQL> SQL> CREATE TABLE project ( 2 pro_id NUMBER(4), 3 pro_name VARCHAR2(40), 4 budget NUMBER(9,2), 5 CONSTRAINT project_pk PRIMARY KEY (pro_id) 6 ); Table created. SQL> SQL> SQL> INSERT INTO project(pro_id, pro_name, budget)VALUES (1001, 'A',12345); 1 row created. SQL> INSERT INTO project(pro_id, pro_name, budget)VALUES (1002, 'ERP',23456); 1 row created. SQL> INSERT INTO project(pro_id, pro_name, budget)VALUES (1003, 'SQL',34567); 1 row created. SQL> INSERT INTO project(pro_id, pro_name, budget)VALUES (1004, 'CRM',45678); 1 row created. SQL> INSERT INTO project(pro_id, pro_name, budget)VALUES (1005, 'VPN',56789); 1 row created. SQL> SQL> SQL> SQL> CREATE TABLE server_usage ( 2 pro_id NUMBER(4), 3 emp_id NUMBER, 4 time_log_date DATE, 5 hours_logged NUMBER(8,2), 6 dollars_charged NUMBER(8,2), 7 CONSTRAINT server_usage_pk PRIMARY KEY (pro_id, emp_id, time_log_date) 8 ); Table created. SQL> INSERT INTO server_usage(pro_id, emp_id, time_log_date, hours_logged, dollars_charged) 2 VALUES (1001,101,to_date('4-Apr-2004','dd-mon-yyyy'),1123,222); 1 row created. SQL> INSERT INTO server_usage(pro_id, emp_id, time_log_date, hours_logged, dollars_charged) 2 VALUES (1002,102,to_date('4-Apr-2005','dd-mon-yyyy'),1124,223); 1 row created. SQL> INSERT INTO server_usage(pro_id, emp_id, time_log_date, hours_logged, dollars_charged) 2 VALUES (1003,103,to_date('4-Apr-2006','dd-mon-yyyy'),1125,224); 1 row created. SQL> INSERT INTO server_usage(pro_id, emp_id, time_log_date, hours_logged, dollars_charged) 2 VALUES (1004,104,to_date('4-Apr-2007','dd-mon-yyyy'),1126,225); 1 row created. SQL> INSERT INTO server_usage(pro_id, emp_id, time_log_date, hours_logged, dollars_charged) 2 VALUES (1005,105,to_date('4-Apr-2008','dd-mon-yyyy'),1127,226); 1 row created. SQL> INSERT INTO server_usage(pro_id, emp_id, time_log_date, hours_logged, dollars_charged) 2 VALUES (1001,106,to_date('4-Apr-2009','dd-mon-yyyy'),1128,227); 1 row created. SQL> INSERT INTO server_usage(pro_id, emp_id, time_log_date, hours_logged, dollars_charged) 2 VALUES (1002,107,to_date('4-Apr-2010','dd-mon-yyyy'),1129,228); 1 row created. SQL> SQL> SQL> SET ECHO ON SQL> SELECT p.pro_name, ph.time_log_date, ph.hours_logged 2 FROM project p LEFT OUTER JOIN server_usage ph 3 ON p.pro_id = ph.pro_id; A 04-APR-04 1123 ERP 04-APR-05 1124 SQL 04-APR-06 1125 CRM 04-APR-07 1126 VPN 04-APR-08 1127 A 04-APR-09 1128 ERP 04-APR-10 1129 7 rows selected. SQL> SQL> SELECT p.pro_name, ph.time_log_date, ph.hours_logged 2 FROM server_usage ph RIGHT OUTER JOIN project p 3 ON p.pro_id = ph.pro_id; A 04-APR-04 1123 ERP 04-APR-05 1124 SQL 04-APR-06 1125 CRM 04-APR-07 1126 VPN 04-APR-08 1127 A 04-APR-09 1128 ERP 04-APR-10 1129 7 rows selected. SQL> SQL> drop table server_usage; Table dropped. SQL> drop table project; Table dropped.