SQL Server/T-SQL/Table Joins/LEFT OUTER JOIN — различия между версиями
Admin (обсуждение | вклад) м (1 версия) |
(нет различий)
|
Текущая версия на 10:19, 26 мая 2010
A LEFT OUTER JOIN includes all the information from the table on the left
1>
2> create table employee(
3> ID int,
4> name nvarchar (10),
5> salary int )
6> GO
1>
2> create table job(
3> ID int,
4> title nvarchar (10),
5> averageSalary int)
6> GO
1>
2>
3> insert into employee (ID, name, salary) values (1, "Jason", 1234)
4> GO
(1 rows affected)
1> insert into employee (ID, name, salary) values (2, "Robert", 4321)
2> GO
(1 rows affected)
1> insert into employee (ID, name, salary) values (3, "Celia", 5432)
2> GO
(1 rows affected)
1> insert into employee (ID, name, salary) values (4, "Linda", 3456)
2> GO
(1 rows affected)
1> insert into employee (ID, name, salary) values (5, "David", 7654)
2> GO
(1 rows affected)
1> insert into employee (ID, name, salary) values (6, "James", 4567)
2> GO
(1 rows affected)
1> insert into employee (ID, name, salary) values (7, "Alison", 8744)
2> GO
(1 rows affected)
1> insert into employee (ID, name, salary) values (8, "Chris", 9875)
2> GO
(1 rows affected)
1> insert into employee (ID, name, salary) values (9, "Mary", 2345)
2> GO
(1 rows affected)
1>
2> insert into job(ID, title, averageSalary) values(1,"Developer",3000)
3> GO
(1 rows affected)
1> insert into job(ID, title, averageSalary) values(2,"Tester", 4000)
2> GO
(1 rows affected)
1> insert into job(ID, title, averageSalary) values(3,"Designer", 5000)
2> GO
(1 rows affected)
1> insert into job(ID, title, averageSalary) values(4,"Programmer", 6000)
2> GO
(1 rows affected)
1>
2>
3> select * from employee;
4> GO
ID name salary
----------- ---------- -----------
1 Jason 1234
2 Robert 4321
3 Celia 5432
4 Linda 3456
5 David 7654
6 James 4567
7 Alison 8744
8 Chris 9875
9 Mary 2345
(9 rows affected)
1> select * from job;
2> GO
ID title averageSalary
----------- ---------- -------------
1 Developer 3000
2 Tester 4000
3 Designer 5000
4 Programmer 6000
(4 rows affected)
1>
2> -- A LEFT OUTER JOIN includes all the information from the table on the left,
3>
4> SELECT e.id, e.name, j.title
5> FROM Employee e
6> LEFT OUTER JOIN job j
7> ON e.id = j.id
8> GO
id name title
----------- ---------- ----------
1 Jason Developer
2 Robert Tester
3 Celia Designer
4 Linda Programmer
5 David NULL
6 James NULL
7 Alison NULL
8 Chris NULL
9 Mary NULL
(9 rows affected)
1>
2> drop table employee;
3> drop table job;
4> GO
1>