SQL Server/T-SQL Tutorial/Table Join/Self join
A self join is really an inner or outer join on the same table.
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Selecting books that have the same price. 8> 9> CREATE TABLE titles( 10> title_id varchar(20), 11> title varchar(80) NOT NULL, 12> type char(12) NOT NULL, 13> pub_id char(4) NULL, 14> price money NULL, 15> advance money NULL, 16> royalty int NULL, 17> ytd_sales int NULL, 18> notes varchar(200) NULL, 19> pubdate datetime NOT NULL 20> ) 21> GO 1> 2> insert titles values ("1", "Secrets", "popular_comp", "1389", $20.00, $8000.00, 10, 4095,"Note 1","06/12/94") 3> insert titles values ("2", "The", "business", "1389", $19.99, $5000.00, 10, 4095,"Note 2","06/12/91") 4> insert titles values ("3", "Emotional", "psychology", "0736", $7.99, $4000.00, 10, 3336,"Note 3","06/12/91") 5> insert titles values ("4", "Prolonged", "psychology", "0736", $19.99, $2000.00, 10, 4072,"Note 4","06/12/91") 6> insert titles values ("5", "With", "business", "1389", $11.95, $5000.00, 10, 3876,"Note 5","06/09/91") 7> insert titles values ("6", "Valley", "mod_cook", "0877", $19.99, $0.00, 12, 2032,"Note 6","06/09/91") 8> insert titles values ("7", "Any?", "trad_cook", "0877", $14.99, $8000.00, 10, 4095,"Note 7","06/12/91") 9> insert titles values ("8", "Fifty", "trad_cook", "0877", $11.95, $4000.00, 14, 1509,"Note 8","06/12/91") 10> GO (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) 1> 2> SELECT DISTINCT t1.price, t1.title 3> FROM titles t1 4> JOIN titles t2 ON t1.price = t2.price 5> AND t1.title_id <> t2.title_id 6> GO price title
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11.9500 Fifty
19.9900 Prolonged
19.9900 The
19.9900 Valley
11.9500 With
(5 rows affected) 1> 2> drop table titles; 3> GO 1> 2></source>
A self-join that returns Bankers from cities in common with other Bankers
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5> 6> create table Billings ( 7> BankerID INTEGER, 8> BillingNumber INTEGER, 9> BillingDate datetime, 10> BillingTotal INTEGER, 11> TermsID INTEGER, 12> BillingDueDate datetime , 13> PaymentTotal INTEGER, 14> CreditTotal INTEGER 15> 16> ); 17> GO 1> 2> INSERT INTO Billings VALUES (1, 1, "2005-01-22", 165, 1,"2005-04-22",123,321); 3> GO (1 rows affected) 1> INSERT INTO Billings VALUES (2, 2, "2001-02-21", 165, 1,"2002-02-22",123,321); 2> GO (1 rows affected) 1> INSERT INTO Billings VALUES (3, 3, "2003-05-02", 165, 1,"2005-04-12",123,321); 2> GO (1 rows affected) 1> INSERT INTO Billings VALUES (4, 4, "1999-03-12", 165, 1,"2005-04-18",123,321); 2> GO (1 rows affected) 1> INSERT INTO Billings VALUES (5, 5, "2000-04-23", 165, 1,"2005-04-17",123,321); 2> GO (1 rows affected) 1> INSERT INTO Billings VALUES (6, 6, "2001-06-14", 165, 1,"2005-04-18",123,321); 2> GO (1 rows affected) 1> INSERT INTO Billings VALUES (7, 7, "2002-07-15", 165, 1,"2005-04-19",123,321); 2> GO (1 rows affected) 1> INSERT INTO Billings VALUES (8, 8, "2003-08-16", 165, 1,"2005-04-20",123,321); 2> GO (1 rows affected) 1> INSERT INTO Billings VALUES (9, 9, "2004-09-17", 165, 1,"2005-04-21",123,321); 2> GO (1 rows affected) 1> INSERT INTO Billings VALUES (0, 0, "2005-10-18", 165, 1,"2005-04-22",123,321); 2> GO (1 rows affected) 1> 2> 3> 4> create table Bankers( 5> BankerID Integer, 6> BankerName VARCHAR(20), 7> BankerContactLName VARCHAR(20), 8> BankerContactFName VARCHAR(20), 9> BankerCity VARCHAR(20), 10> BankerState VARCHAR(20), 11> BankerZipCode VARCHAR(20), 12> BankerPhone VARCHAR(20) 13> ) 14> GO 1> 2> insert into Bankers values (1, "ABC Inc.","Joe","Smith","Vancouver","BC","11111","111-111-1111"); 3> GO (1 rows affected) 1> insert into Bankers values (2, "DEF Inc.","Red","Rice", "New York", "DE","22222","222-222-2222"); 2> GO (1 rows affected) 1> insert into Bankers values (3, "HJI Inc.","Kit","Cat", "Paris", "CA","33333","333-333-3333"); 2> GO (1 rows affected) 1> insert into Bankers values (4, "QWE Inc.","Git","Black","Regina", "ER","44444","444-444-4444"); 2> GO (1 rows affected) 1> insert into Bankers values (5, "RTY Inc.","Wil","Lee", "Toronto", "YU","55555","555-555-5555"); 2> GO (1 rows affected) 1> insert into Bankers values (6, "YUI Inc.","Ted","Larry","Calgary", "TY","66666","666-666-6666"); 2> GO (1 rows affected) 1> insert into Bankers values (7, "OIP Inc.","Yam","Act", "San Franc","FG","77777","777-777-7777"); 2> GO (1 rows affected) 1> insert into Bankers values (8, "SAD Inc.","Hit","Eat", "Orland", "PO","88888","888-888-8888"); 2> GO (1 rows affected) 1> insert into Bankers values (9, "DFG Inc.","Sad","Lee", "Wisler", "PL","99999","999-999-9999"); 2> GO (1 rows affected) 1> insert into Bankers values (0, "GHJ Inc.","Bit","Lee", "Ticker", "MN","00000","000-000-0000"); 2> GO (1 rows affected) 1> 2> 3> 4> 5> SELECT DISTINCT Bankers1.BankerName, Bankers1.BankerCity, 6> Bankers1.BankerState 7> FROM Bankers AS Bankers1 JOIN Bankers AS Bankers2 8> ON (Bankers1.BankerCity = Bankers2.BankerCity) AND 9> (Bankers1.BankerState = Bankers2.BankerState) AND 10> (Bankers1.BankerID <> Bankers2.BankerID) 11> ORDER BY Bankers1.BankerState, Bankers1.BankerCity 12> GO BankerName BankerCity BankerState
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(0 rows affected) 1> 2> drop table Bankers; 3> drop table Billings; 4> GO 1></source>
Set join condition in ON clause
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2> CREATE TABLE authors( 3> au_id varchar(11), 4> au_lname varchar(40) NOT NULL, 5> au_fname varchar(20) NOT NULL, 6> phone char(12) NOT NULL DEFAULT ("UNKNOWN"), 7> address varchar(40) NULL, 8> city varchar(20) NULL, 9> state char(2) NULL, 10> zip char(5) NULL, 11> contract bit NOT NULL 12> ) 13> GO 1> insert authors values("1", "Joe", "Abra", "111 111-1111", "6 St.", "Berkeley", "CA", "11111", 1) 2> insert authors values("2", "Jack", "Majo", "222 222-2222", "3 St.", "Oakland" , "CA", "22222", 1) 3> insert authors values("3", "Pink", "Cherry", "333 333-3333", "5 Ln.", "Vancouver", "BC", "33333", 1) 4> insert authors values("4", "Blue", "Albert", "444 444-4444", "7 Av.", "Vancouver", "BC", "44444", 1) 5> insert authors values("5", "Red", "Anne", "555 555-5555", "6 Av.", "Regina", "SK", "55555", 1) 6> insert authors values("6", "Black", "Michel", "666 666-6666", "3 Pl.", "Regina", "SK", "66666", 1) 7> insert authors values("7", "White", "Sylvia", "777 777-7777", "1 Pl.", "Rockville", "MD", "77777", 1) 8> insert authors values("8", "Yellow","Heather","888 888-8888", "3 Pu", "Vacaville", "CA", "88888", 0) 9> insert authors values("9", "Gold", "Dep", "999 999-9999", "5 Av.", "Oakland", "CA", "99999", 0) 10> insert authors values("10", "Siler", "Dean", "000 000-0000", "4 Av.", "Oakland", "CA", "00000", 1) 11> GO (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) 1> 2> CREATE TABLE titles( 3> title_id varchar(20), 4> title varchar(80) NOT NULL, 5> type char(12) NOT NULL, 6> pub_id char(4) NULL, 7> price money NULL, 8> advance money NULL, 9> royalty int NULL, 10> ytd_sales int NULL, 11> notes varchar(200) NULL, 12> pubdate datetime NOT NULL 13> ) 14> GO 1> 2> insert titles values ("1", "Secrets", "popular_comp", "1389", $20.00, $8000.00, 10, 4095,"Note 1","06/12/94") 3> insert titles values ("2", "The", "business", "1389", $19.99, $5000.00, 10, 4095,"Note 2","06/12/91") 4> insert titles values ("3", "Emotional", "psychology", "0736", $7.99, $4000.00, 10, 3336,"Note 3","06/12/91") 5> insert titles values ("4", "Prolonged", "psychology", "0736", $19.99, $2000.00, 10, 4072,"Note 4","06/12/91") 6> insert titles values ("5", "With", "business", "1389", $11.95, $5000.00, 10, 3876,"Note 5","06/09/91") 7> insert titles values ("6", "Valley", "mod_cook", "0877", $19.99, $0.00, 12, 2032,"Note 6","06/09/91") 8> insert titles values ("7", "Any?", "trad_cook", "0877", $14.99, $8000.00, 10, 4095,"Note 7","06/12/91") 9> insert titles values ("8", "Fifty", "trad_cook", "0877", $11.95, $4000.00, 14, 1509,"Note 8","06/12/91") 10> GO (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) 1> 2> CREATE TABLE titleauthor( 3> au_id varchar(20), 4> title_id varchar(20), 5> au_ord tinyint NULL, 6> royaltyper int NULL 7> ) 8> GO 1> 2> insert titleauthor values("1", "2", 1, 60) 3> insert titleauthor values("2", "3", 1, 100) 4> insert titleauthor values("3", "4", 1, 100) 5> insert titleauthor values("4", "5", 1, 100) 6> insert titleauthor values("5", "6", 1, 100) 7> insert titleauthor values("6", "7", 2, 40) 8> insert titleauthor values("7", "8", 1, 100) 9> insert titleauthor values("8", "9", 1, 100) 10> GO (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) (1 rows affected) 1> 2> 3> 4> SELECT 5> "Author"=RTRIM(au_lname) + ", " + au_fname, 6> "Title"=title 7> FROM authors AS A JOIN titleauthor AS TA 8> ON A.au_id=TA.au_id -- JOIN CONDITION 9> JOIN titles AS T 10> ON T.title_id=TA.title_id -- JOIN CONDITION 11> WHERE A.state <> "CA" 12> ORDER BY 1 13> GO Author Title
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Black, Michel Any? Black, Michel Any? Blue, Albert With Blue, Albert With Pink, Cherry Prolonged Pink, Cherry Prolonged Red, Anne Valley Red, Anne Valley White, Sylvia Fifty White, Sylvia Fifty (10 rows affected) 1> 2> drop table authors; 3> drop table titles; 5> GO 1></source>
