SQL Server/T-SQL/Table Joins/INNER JOIN

Inner join with condition on joined field

1> create table employee(
2>     ID          int,
3>     name        nvarchar (10),
4>     salary      int )
5> 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>
3> SELECT p.ID, s.title, p.Name
4> FROM Employee p
5> INNER JOIN Job s
6>         ON p.ID = s.ID
7> WHERE p.ID < 4
8> GO
ID          title      Name
----------- ---------- ----------
          1 Developer  Jason
          2 Tester     Robert
          3 Designer   Celia
(3 rows affected)
1>
2>
3>
4> drop table employee;
5> drop table job;
6> GO
1>
2>

"INNER JOIN" with different syntax

1>
2>
3> create table employee(
4>     ID          int,
5>     name        nvarchar (10),
6>     salary      int )
7> 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>
3> -- INNER JOINs
4>
5> SELECT * FROM Employee
6> INNER JOIN job
7>         ON Employee.ID = Job.ID
8>
9> GO
ID          name       salary      ID          title      averageSalary
----------- ---------- ----------- ----------- ---------- -------------
          1 Jason             1234           1 Developer           3000
          2 Robert            4321           2 Tester              4000
          3 Celia             5432           3 Designer            5000
          4 Linda             3456           4 Programmer          6000
(4 rows affected)
1>
2>
3>
4> drop table employee;
5> drop table job;
6> GO
1>

Using the * operator to reference entire row

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> -- Using the * operator
3>
4>
5> SELECT Employee.* FROM Employee
6> INNER JOIN Job
7>         ON Employee.ID = Job.ID
8> GO
ID          name       salary
----------- ---------- -----------
          1 Jason             1234
          2 Robert            4321
          3 Celia             5432
          4 Linda             3456
(4 rows affected)
1>
2>
3> drop table employee;
4> drop table job;
5> GO
1>

Working with "INNER JOIN"

1> create table employee(
2>     ID          int,
3>     name        nvarchar (10),
4>     salary      int )
5> 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>
3> insert into job(ID, title, averageSalary) values(1,"Developer",3000)
4> 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> select * from employee;
3> 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>
3> SELECT e.ID, e.Name, j.title
4> FROM Employee e INNER JOIN Job j
5> ON e.Id = j.ID
6> GO
ID          Name       title
----------- ---------- ----------
          1 Jason      Developer
          2 Robert     Tester
          3 Celia      Designer
          4 Linda      Programmer
(4 rows affected)
1>
2>
3>
4> drop table employee;
5> drop table job;
6> GO
1>