| Demo Tables & Data |
Join Demo Tables |
CREATE TABLE person (
person_id NUMBER(10),
first_name VARCHAR2(25) NOT NULL,
last_name VARCHAR2(25) NOT NULL,
title_1 VARCHAR2(5),
title_2 VARCHAR2(5))
PCTFREE 20;
ALTER TABLE person
ADD CONSTRAINT pk_person
PRIMARY KEY (person_id)
USING INDEX
PCTFREE 5;
CREATE TABLE person_role (
role_id VARCHAR2(1),
role_name VARCHAR2(20) NOT NULL);
ALTER TABLE person_role
ADD CONSTRAINT pk_role
PRIMARY KEY (role_id)
USING INDEX
PCTFREE 5;
CREATE TABLE person_role_ie (
person_role_id NUMBER(10),
person_id NUMBER(10) NOT NULL,
role_id VARCHAR2(1) NOT NULL);
ALTER TABLE person_role_ie
ADD CONSTRAINT pk_person_role_ie
PRIMARY KEY (person_role_id)
USING INDEX
PCTFREE 5;
CREATE TABLE title (
title_abbrev VARCHAR2(5),
title_name VARCHAR2(20))
PCTFREE 0;
ALTER TABLE title
ADD CONSTRAINT pk_title
PRIMARY KEY (title_abbrev)
USING INDEX
PCTFREE 0;
ALTER TABLE person_role_ie
ADD CONSTRAINT fk_person_role_ie_person
FOREIGN KEY (person_id)
REFERENCES person(person_id);
ALTER TABLE person_role_ie
ADD CONSTRAINT fk_person_role_ie_role
FOREIGN KEY (role_id)
REFERENCES person_role(role_id);
ALTER TABLE person
ADD CONSTRAINT fk_person_title1
FOREIGN KEY (title_1)
REFERENCES title(title_abbrev);
ALTER TABLE person
ADD CONSTRAINT fk_person_title2
FOREIGN KEY (title_2)
REFERENCES title(title_abbrev); |
Demo Table Data Load |
INSERT INTO title VALUES
('BA', 'Bachelor of Arts');
INSERT INTO title VALUES
('BS', 'Bachelor of Science');
INSERT INTO title VALUES
('MS', 'Master of Science');
INSERT INTO title VALUES
('PhD', 'Doctor of Philosophy');
INSERT INTO title VALUES
('MD', 'Doctor of Medicine');
INSERT INTO person
(person_id, first_name, last_name, title_1)
VALUES
(1, 'Daniel', 'Morgan', 'BS');
INSERT INTO person
(person_id, first_name, last_name, title_1)
VALUES
(2, 'Jack', 'Cline', 'BA');
INSERT INTO person
(person_id, first_name, last_name, title_1)
VALUES
(3, 'Muriel', 'Dance', 'PhD');
INSERT INTO person
(person_id, first_name, last_name, title_1)
VALUES
(4, 'Elizabeth', 'Scott', 'MS');
INSERT INTO person
(person_id, first_name, last_name)
VALUES
(5, 'Jacqueline', 'Stough');
INSERT INTO person_role VALUES (1, 'Administrator');
INSERT INTO person_role VALUES (2, 'Professor');
INSERT INTO person_role VALUES (3, 'Instructor');
INSERT INTO person_role VALUES (4, 'Employee');
INSERT INTO person_role VALUES (5, 'Student');
INSERT INTO person_role VALUES (9, 'Alumni');
CREATE SEQUENCE seq_pr_id START WITH 1;
INSERT INTO person_role_ie VALUES
(seq_pr_id.NEXTVAL, 1, 2);
INSERT INTO person_role_ie VALUES
(seq_pr_id.NEXTVAL, 1, 9);
INSERT INTO person_role_ie VALUES
(seq_pr_id.NEXTVAL, 2, 3);
INSERT INTO person_role_ie VALUES
(seq_pr_id.NEXTVAL, 1, 5);
INSERT INTO person_role_ie VALUES
(seq_pr_id.NEXTVAL, 3, 1);
INSERT INTO person_role_ie VALUES
(seq_pr_id.NEXTVAL, 3, 9);
INSERT INTO person_role_ie VALUES
(seq_pr_id.NEXTVAL, 4, 4);
INSERT INTO person_role_ie VALUES
(seq_pr_id.NEXTVAL, 5, 5);
INSERT INTO person_role_ie VALUES
(seq_pr_id.NEXTVAL, 5, 9);
COMMIT; |
| |
| Traditional Joins |
Two Table Inner Join |
SELECT <column_name>, <column_name>
FROM <table_name alias>, <table_name alias>
WHERE <alias.column_name> = <alias.column_name> |
SELECT p.last_name, t.title_name
FROM person p, title t
WHERE p.title_1 = t.title_abbrev; |
Three Table Inner Join |
SELECT <column_name>, <column_name>
FROM <table_name alias>, <table_name alias>
WHERE <alias.column_name> = <alias.column_name>
AND <alias.column_name> = <alias.column_name>; |
SELECT p.last_name, r.role_name
FROM person p, person_role_ie i, person_role r
WHERE p.person_id = i.person_id
AND i.role_id = r.role_id
ORDER BY p.person_id; |
Left Outer Join |
SELECT <column_name>, <column_name>
FROM <table_name alias>, <table_name alias>
WHERE <alias.column_name = <alias.column_name>
AND <alias.column_name> = <alias.column_name> (+); |
SELECT p.last_name, t.title_name
FROM person p, title t
WHERE p.title_1 = t.title_abbrev(+); |
Right Outer Join |
SELECT <column_name>, <column_name>
FROM <table_name alias>, <table_name alias>
WHERE <alias.column_name> (+) = <alias.column_name>; |
SELECT p.last_name, t.title_name
FROM person p, title t
WHERE p.title_1(+) = t.title_abbrev; |
Self Join |
SELECT <column_name>, <column_name>
FROM <table_name alias>, <table_name alias>, <table_name alias>
WHERE <alias.column_name> = < alias.column_name>
AND <alias.column_name> = <alias.column_name>; |
UPDATE person
SET title_2 = 'PhD'
WHERE person_id = 1;
COMMIT;
SELECT p.last_name, t1.title_name, t2.title_name
FROM person p, title t1, title t2
WHERE p.title_1 = t1.title_abbrev
AND p.title_2 = t2.title_abbrev; |
| |
| ANSI Joins |
Inner Join |
SELECT <column_name>, <column_name>
FROM <table_name alias> INNER JOIN <table_name alias>
ON <alias.column_name> = <alias.column_name> |
SELECT p.last_name, t.title_name
FROM person p INNER JOIN title t
ON p.title_1 = t.title_abbrev; |
Left Outer Join |
SELECT <column_name>, <column_name>
FROM <table_name alias> LEFT OUTER JOIN <table_name alias>
ON <alias.column_name> = <alias.column_name> |
SELECT p.last_name, t.title_name
FROM person p LEFT OUTER JOIN title t
ON p.title_1 = t.title_abbrev; |
Right Outer Join |
SELECT <column_name>, <column_name>
FROM <table_name alias> RIGHT OUTER JOIN <table_name alias>
ON <alias.column_name> = <alias.column_name> |
SELECT p.last_name, t.title_name
FROM person p RIGHT OUTER JOIN title t
ON p.title_1 = t.title_abbrev; |
Full Outer Join |
SELECT <column_name>, <column_name>
FROM <table_name alias> FULL OUTER JOIN <table_name alias>
ON <alias.column_name> = <alias.column_name> |
SELECT p.last_name, t.title_name
FROM person p FULL OUTER JOIN title t
ON p.title_1 = t.title_abbrev; |
Natural Join |
SELECT <column_name>, <column_name>
FROM <table_name alias> NATURAL JOIN <table_name alias> |
CREATE TABLE parents (
person_id NUMBER(5),
adult_name VARCHAR2(20),
comments VARCHAR2(40))
PCTFREE 0;
CREATE TABLE children (
parent_id NUMBER(5),
person_id NUMBER(5),
child_name VARCHAR2(20),
comments VARCHAR2(40))
PCTFREE 0;
INSERT INTO parents VALUES (1, 'Dan', 'So What');
INSERT INTO parents VALUES (2, 'Jack', 'Who Cares');
INSERT INTO children VALUES (1, 2, 'Anne', 'Who Cares');
INSERT INTO children VALUES (1, 1, 'Julia', 'Yeah Right');
INSERT INTO children VALUES (2, 1, 'Marcella', 'So What');
COMMIT;
SELECT adult_name, child_name
FROM parents NATURAL JOIN children; |
Self Join |
SELECT <column_name>, <column_name>
FROM <table_name alias> INNER JOIN <table_name alias>
ON <alias.column_name> = <alias.column_name>,
<table_name alias> INNER JOIN <table_name alias>
ON <alias .column_name> = <alias.column_name>; |
SELECT p1.last_name, t1.title_name, t2.title_name
FROM person p1 INNER JOIN title t1
ON p1.title_1 = t1.title_abbrev,
person p2 INNER JOIN title t2
ON p2.title_2 = t2.title_abbrev;
EXPLAIN PLAN FOR
SELECT p1.last_name, t1.title_name, t2.title_name
FROM person p1 INNER JOIN title t1
ON p1.title_1 = t1.title_abbrev,
person p2 INNER JOIN title t2
ON p2.title_2 = t2.title_abbrev;
SELECT * FROM TABLE(dbms_xplan.display);
-----------------------------------------------------------------------
| Id | Operation | Name | Rows | Cost (%CPU)|
-----------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 16 (0)|
| 1 | NESTED LOOPS | | | |
| 2 | NESTED LOOPS | | 1 | 16 (0)|
| 3 | MERGE JOIN CARTESIAN | | 1 | 15 (0)|
| 4 | NESTED LOOPS | | | |
| 5 | NESTED LOOPS | | 1 | 10 (0)|
| 6 | TABLE ACCESS FULL | PERSON | 5 | 5 (0)|
| 7 | INDEX UNIQUE SCAN | PK_TITLE | 1 | 0 (0)|
| 8 | TABLE ACCESS BY INDEX ROWID| TITLE | 1 | 1 (0)|
| 9 | BUFFER SORT | | 5 | 14 (0)|
| 10 | TABLE ACCESS FULL | PERSON | 5 | 5 (0)|
| 11 | INDEX UNIQUE SCAN | PK_TITLE | 1 | 0 (0)|
| 12 | TABLE ACCESS BY INDEX ROWID | TITLE | 1 | 1 (0)|
----------------------------------------------------------------------- |
Alternative Syntax Joining on commonly named column in both tables |
SELECT <column_name>, <column_name>
FROM <table_name alias> <join_type> <table_name alias>
USING (<common_column_name>); |
-- does not work
SELECT s.srvr_id, s.status, i.location_code
FROM servers s INNER JOIN serv_inst i
USING (s.srvr_id)
WHERE rownum < 11;
-- does not work either
SELECT s.srvr_id, s.status, i.location_code
FROM servers s INNER JOIN serv_inst i
USING (srvr_id)
WHERE rownum < 11;
-- works
SELECT srvr_id, s.status, i.location_code
FROM servers s INNER JOIN serv_inst i
USING (srvr_id)
WHERE rownum < 11; |
| |
| Cartesian Join |
Table And Data For Cartesian
Product (Cross-Join) Demo |
CREATE TABLE cartesian (
join_column NUMBER(10));
CREATE TABLE product (
join_column NUMBER(10)); |
Load Demo Tables |
BEGIN
FOR i in 1..1000
LOOP
INSERT INTO cartesian VALUES (i);
INSERT INTO product VALUES (i);
END LOOP;
COMMIT;
END;
/ |
Inner Join |
SELECT COUNT(*)
FROM cartesian c, product p
WHERE c.join_column = p.join_column;
EXPLAIN PLAN FOR
SELECT COUNT(*)
FROM cartesian c, product p
WHERE c.join_column = p.join_column;
SELECT * FROM TABLE(dbms_xplan.display);
--------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)|
--------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 26 | 11 (10)|
| 1 | SORT AGGREGATE | | 1 | 26 | |
| 2 | HASH JOIN | | 1000 | 26000 | 11 (10)|
| 3 | TABLE ACCESS FULL| CARTESIAN | 1000 | 13000 | 5 (0)|
| 4 | TABLE ACCESS FULL| PRODUCT | 1000 | 13000 | 5 (0)|
-------------------------------------------------------------------- |
Not Inner Join |
SELECT COUNT(*)
FROM cartesian c, product p
WHERE c.join_column != p.join_column;
EXPLAIN PLAN FOR
SELECT COUNT(*)
FROM cartesian c, product p
WHERE c.join_column != p.join_column;
SELECT * FROM TABLE(dbms_xplan.display);
--------------------------------------------------------------------
| Id | Operation | Name | Rows | Bytes | Cost (%CPU)|
--------------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 26 | 3076 (2)|
| 1 | SORT AGGREGATE | | 1 | 26 | |
| 2 | NESTED LOOPS | | 999K| 24M| 3076 (2)|
| 3 | TABLE ACCESS FULL| CARTESIAN | 1000 | 13000 | 5 (0)|
| 4 | TABLE ACCESS FULL| PRODUCT | 999 | 12987 | 3 (0)|
-------------------------------------------------------------------- |
Cartesian (Cross-Join) Product |
SELECT COUNT(*)
FROM cartesian, product;
EXPLAIN PLAN FOR
SELECT COUNT(*)
FROM cartesian c, product p;
SELECT * FROM TABLE(dbms_xplan.display);
----------------------------------------------------------------
| Id | Operation | Name | Rows | Cost (%CPU)|
----------------------------------------------------------------
| 0 | SELECT STATEMENT | | 1 | 3076 (2)|
| 1 | SORT AGGREGATE | | 1 | |
| 2 | MERGE JOIN CARTESIAN| | 1000K| 3076 (2)|
| 3 | TABLE ACCESS FULL | CARTESIAN | 1000 | 5 (0)|
| 4 | BUFFER SORT | | 1000 | 3071 (2)|
| 5 | TABLE ACCESS FULL | PRODUCT | 1000 | 3 (0)|
---------------------------------------------------------------- |
Intentional Cartesian (Cross-Join) Product |
SELECT <alias.column_name>, <alias.column_name>
FROM <table_name alias> CROSS JOIN <table_name alias>; |
SELECT s.srvr_id, i.location_code
FROM servers s CROSS JOIN serv_inst i
WHERE rownum < 1001;
|
| |
| Join Related Queries |
Column Join Usage |
conn / as sysdba
set linesize 121
desc col_usage$
SELECT *
FROM col_usage$
WHERE obj# IN (
SELECT object_id
FROM dba_objects
WHERE owner = 'UWCLASS'); |
