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2010-05-26T13:45:46Z

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== Join table using==



<source lang="sql">
SQL> create table emp
2 ( empno NUMBER(4) constraint E_PK primary key
3 , ename VARCHAR2(8)
4 , init VARCHAR2(5)
5 , job VARCHAR2(8)
6 , mgr NUMBER(4)
7 , bdate DATE
8 , sal NUMBER(6,2)
9 , comm NUMBER(6,2)
10 , deptno NUMBER(2) default 10
11 ) ;
Table created.
SQL> insert into emp values(1,"Tom","N", "Coder", 13,date "1965-12-17", 800 , NULL, 20);
1 row created.
SQL> insert into emp values(2,"Jack","JAM", "Tester",6,date "1961-02-20", 1600, 300, 30);
1 row created.
SQL> insert into emp values(3,"Wil","TF" , "Tester",6,date "1962-02-22", 1250, 500, 30);
1 row created.
SQL> insert into emp values(4,"Jane","JM", "Designer", 9,date "1967-04-02", 2975, NULL, 20);
1 row created.
SQL> insert into emp values(5,"Mary","P", "Tester",6,date "1956-09-28", 1250, 1400, 30);
1 row created.
SQL> insert into emp values(6,"Black","R", "Designer", 9,date "1963-11-01", 2850, NULL, 30);
1 row created.
SQL> insert into emp values(7,"Chris","AB", "Designer", 9,date "1965-06-09", 2450, NULL, 10);
1 row created.
SQL> insert into emp values(8,"Smart","SCJ", "Coder", 4,date "1959-11-26", 3000, NULL, 20);
1 row created.
SQL> insert into emp values(9,"Peter","CC", "Designer",NULL,date "1952-11-17", 5000, NULL, 10);
1 row created.
SQL> insert into emp values(10,"Take","JJ", "Tester",6,date "1968-09-28", 1500, 0, 30);
1 row created.
SQL> insert into emp values(11,"Ana","AA", "Coder", 8,date "1966-12-30", 1100, NULL, 20);
1 row created.
SQL> insert into emp values(12,"Jane","R", "Manager", 6,date "1969-12-03", 800 , NULL, 30);
1 row created.
SQL> insert into emp values(13,"Fake","MG", "Coder", 4,date "1959-02-13", 3000, NULL, 20);
1 row created.
SQL> insert into emp values(14,"Mike","TJA","Manager", 7,date "1962-01-23", 1300, NULL, 10);
1 row created.
SQL> create table history
2 ( empno NUMBER(4)
3 , beginyear NUMBER(4)
4 , begindate DATE
5 , enddate DATE
6 , deptno NUMBER(2)
7 , sal NUMBER(6,2)
8 , comments VARCHAR2(60)
9 , constraint H_PK primary key(empno,begindate)
10 , constraint H_BEG_END check (begindate < enddate)
11 ) ;
Table created.
SQL>
SQL>
SQL> alter session set NLS_DATE_FORMAT="DD-MM-YYYY";
Session altered.
SQL>
SQL> insert into history values (1,2000,"01-01-2000","01-02-2000",40, 950,"");
1 row created.
SQL> insert into history values (1,2000,"01-02-2000", NULL ,20, 800,"restarted");
1 row created.
SQL> insert into history values (2,2009,"01-11-2009", NULL ,30,1600,"just hired");
1 row created.
SQL> insert into history values (3,1987,"01-08-1987","01-01-1989",30,1000,"On training");
1 row created.
SQL> insert into history values (3,2000,"01-02-2000", NULL ,30,1250,"");
1 row created.
SQL>
SQL> select e.ename, e.bdate
2 , h.deptno, h.sal
3 from emp e
4 join
5 history h
6 using (empno)
7 where e.job = "Manager";
no rows selected
SQL>
SQL> drop table history;
Table dropped.
SQL> drop table emp;
Table dropped.</source>

== Simplifying Joins with the USING Keyword==

SQL/92 allows you to further simplify the join condition through the USING clause, but only when your query has the following limitations:
Your query must use an equijoin.
The columns in your equijoin have the same name.
Don"t use a table name or alias when referencing columns used in a USING clause.



<source lang="sql">
SQL> -- create demo table
SQL> create table Employee(
2 EMPNO NUMBER(3),
3 ENAME VARCHAR2(15 BYTE),
4 HIREDATE DATE,
5 ORIG_SALARY NUMBER(6),
6 CURR_SALARY NUMBER(6),
7 REGION VARCHAR2(1 BYTE),
8 MANAGER_ID NUMBER(3)
9 )
10 /
Table created.
SQL>
SQL> create table job (
2 EMPNO NUMBER(3),
3 jobtitle VARCHAR2(20 BYTE)
4 )
5 /
Table created.
SQL>
SQL> insert into job (EMPNO, Jobtitle) values (1,"Tester");
1 row created.
SQL> insert into job (EMPNO, Jobtitle) values (2,"Accountant");
1 row created.
SQL> insert into job (EMPNO, Jobtitle) values (3,"Developer");
1 row created.
SQL> insert into job (EMPNO, Jobtitle) values (4,"COder");
1 row created.
SQL> insert into job (EMPNO, Jobtitle) values (5,"Director");
1 row created.
SQL> insert into job (EMPNO, Jobtitle) values (6,"Mediator");
1 row created.
SQL> insert into job (EMPNO, Jobtitle) values (7,"Proffessor");
1 row created.
SQL> insert into job (EMPNO, Jobtitle) values (8,"Programmer");
1 row created.
SQL> insert into job (EMPNO, Jobtitle) values (9,"Developer");
1 row created.
SQL>
SQL>
SQL> -- prepare data
SQL> insert into Employee(EMPNO, EName, HIREDATE, ORIG_SALARY, CURR_SALARY, REGION, MANAGER_ID)
2 values (1, "Jason", to_date("19960725","YYYYMMDD"), 1234, 8767, "E", 2)
3 /
1 row created.
SQL> insert into Employee(EMPNO, EName, HIREDATE, ORIG_SALARY, CURR_SALARY, REGION, MANAGER_ID)
2 values (2, "John", to_date("19970715","YYYYMMDD"), 2341, 3456, "W", 3)
3 /
1 row created.
SQL> insert into Employee(EMPNO, EName, HIREDATE, ORIG_SALARY, CURR_SALARY, REGION, MANAGER_ID)
2 values (3, "Joe", to_date("19860125","YYYYMMDD"), 4321, 5654, "E", 3)
3 /
1 row created.
SQL> insert into Employee(EMPNO, EName, HIREDATE, ORIG_SALARY, CURR_SALARY, REGION, MANAGER_ID)
2 values (4, "Tom", to_date("20060913","YYYYMMDD"), 2413, 6787, "W", 4)
3 /
1 row created.
SQL> insert into Employee(EMPNO, EName, HIREDATE, ORIG_SALARY, CURR_SALARY, REGION, MANAGER_ID)
2 values (5, "Jane", to_date("20050417","YYYYMMDD"), 7654, 4345, "E", 4)
3 /
1 row created.
SQL> insert into Employee(EMPNO, EName, HIREDATE, ORIG_SALARY, CURR_SALARY, REGION, MANAGER_ID)
2 values (6, "James", to_date("20040718","YYYYMMDD"), 5679, 6546, "W", 5)
3 /
1 row created.
SQL> insert into Employee(EMPNO, EName, HIREDATE, ORIG_SALARY, CURR_SALARY, REGION, MANAGER_ID)
2 values (7, "Jodd", to_date("20030720","YYYYMMDD"), 5438, 7658, "E", 6)
3 /
1 row created.
SQL> insert into Employee(EMPNO, EName, HIREDATE, ORIG_SALARY, CURR_SALARY, REGION)
2 values (8, "Joke", to_date("20020101","YYYYMMDD"), 8765, 4543, "W")
3 /
1 row created.
SQL> insert into Employee(EMPNO, EName, HIREDATE, ORIG_SALARY, CURR_SALARY, REGION)
2 values (9, "Jack", to_date("20010829","YYYYMMDD"), 7896, 1232, "E")
3 /
1 row created.
SQL>
SQL>
SQL>
SQL> -- display data in the table
SQL> select * from Employee
2 /
EMPNO ENAME HIREDATE ORIG_SALARY CURR_SALARY R MANAGER_ID
---------- --------------- --------- ----------- ----------- - ----------
1 Jason 25-JUL-96 1234 8767 E 2
2 John 15-JUL-97 2341 3456 W 3
3 Joe 25-JAN-86 4321 5654 E 3
4 Tom 13-SEP-06 2413 6787 W 4
5 Jane 17-APR-05 7654 4345 E 4
6 James 18-JUL-04 5679 6546 W 5
7 Jodd 20-JUL-03 5438 7658 E 6
8 Joke 01-JAN-02 8765 4543 W
9 Jack 29-AUG-01 7896 1232 E
9 rows selected.
SQL> select * from job
2 /
EMPNO JOBTITLE
---------- --------------------
1 Tester
2 Accountant
3 Developer
4 COder
5 Director
6 Mediator
7 Proffessor
8 Programmer
9 Developer
9 rows selected.
SQL>
SQL> SELECT e.ename, j.jobtitle FROM employee e INNER JOIN job j USING (empno);
ENAME JOBTITLE
--------------- --------------------
Jason Tester
John Accountant
Joe Developer
Tom COder
Jane Director
James Mediator
Jodd Proffessor
Joke Programmer
Jack Developer
9 rows selected.
SQL>
SQL>
SQL> -- clean the table
SQL> drop table Employee
2 /
Table dropped.
SQL> drop table job
2 /
Table dropped.
SQL></source>

== Using clause for table join==



<source lang="sql">
SQL>
SQL>
SQL>
SQL> create table employees(
2 empno NUMBER(4)
3 , ename VARCHAR2(8)
4 , init VARCHAR2(5)
5 , job VARCHAR2(8)
6 , mgr NUMBER(4)
7 , bdate DATE
8 , msal NUMBER(6,2)
9 , comm NUMBER(6,2)
10 , deptno NUMBER(2) ) ;
Table created.
SQL>
SQL>
SQL> insert into employees values(1,"Jason", "N", "TRAINER", 2, date "1965-12-18", 800 , NULL, 10);
1 row created.
SQL> insert into employees values(2,"Jerry", "J", "SALESREP",3, date "1966-11-19", 1600, 300, 10);
1 row created.
SQL> insert into employees values(3,"Jord", "T" , "SALESREP",4, date "1967-10-21", 1700, 500, 20);
1 row created.
SQL> insert into employees values(4,"Mary", "J", "MANAGER", 5, date "1968-09-22", 1800, NULL, 20);
1 row created.
SQL> insert into employees values(5,"Joe", "P", "SALESREP",6, date "1969-08-23", 1900, 1400, 30);
1 row created.
SQL> insert into employees values(6,"Black", "R", "MANAGER", 7, date "1970-07-24", 2000, NULL, 30);
1 row created.
SQL> insert into employees values(7,"Red", "A", "MANAGER", 8, date "1971-06-25", 2100, NULL, 40);
1 row created.
SQL> insert into employees values(8,"White", "S", "TRAINER", 9, date "1972-05-26", 2200, NULL, 40);
1 row created.
SQL> insert into employees values(9,"Yellow", "C", "DIRECTOR",10, date "1973-04-27", 2300, NULL, 20);
1 row created.
SQL> insert into employees values(10,"Pink", "J", "SALESREP",null,date "1974-03-28", 2400, 0, 30);
1 row created.
SQL>
SQL>
SQL>
SQL> create table history
2 ( empno NUMBER(4)
3 , beginyear NUMBER(4)
4 , begindate DATE
5 , enddate DATE
6 , deptno NUMBER(2)
7 , msal NUMBER(6,2)
8 , comments VARCHAR2(60)
9 ) ;
Table created.
SQL>
SQL>
SQL>
SQL> insert into history values (9,2000,date "2000-01-01",date "2002-01-02",40, 950,"history for 9");
1 row created.
SQL> insert into history values (8,2000,date "2000-01-02", NULL ,20, 800,"");
1 row created.
SQL> insert into history values (7,1988,date "2000-01-06",date "2002-01-07",30,1000,"");
1 row created.
SQL> insert into history values (6,1989,date "2000-01-07",date "2002-01-12",30,1300,"");
1 row created.
SQL> insert into history values (5,1993,date "2000-01-12",date "2002-01-10",30,1500,"history for 5");
1 row created.
SQL> insert into history values (4,1995,date "2000-01-10",date "2002-01-11",30,1700,"");
1 row created.
SQL> insert into history values (3,1999,date "2000-01-11", NULL ,30,1600,"");
1 row created.
SQL> insert into history values (2,1986,date "2000-01-10",date "2002-01-08",20,1000,"history for 2");
1 row created.
SQL> insert into history values (1,1987,date "2000-01-08",date "2002-01-01",30,1000,"history for 1");
1 row created.
SQL> insert into history values (7,1989,date "2000-01-01",date "2002-05-12",30,1150,"history for 7");
1 row created.
SQL>
SQL>
SQL>
SQL>
SQL> select e.ename, e.bdate
2 , h.deptno, h.msal
3 from employees e
4 join
5 history h
6 using (empno)
7 where e.job = "MANAGER";
ENAME BDATE DEPTNO MSAL
-------- --------- ---------- ----------
Red 25-JUN-71 30 1000
Black 24-JUL-70 30 1300
Mary 22-SEP-68 30 1700
Red 25-JUN-71 30 1150
SQL>
SQL>
SQL>
SQL> drop table history;
Table dropped.
SQL>
SQL> drop table employees;
Table dropped.
SQL></source>

== Using two columns during table join==



<source lang="sql">
SQL>
SQL>
SQL>
SQL> create table course_schedule
2 ( course VARCHAR2(6)
3 , begindate DATE
4 , trainer NUMBER(4)
5 , location VARCHAR2(20)) ;
Table created.
SQL>
SQL>
SQL> insert into course_schedule values ("SQL",date "1999-04-12",1,"VANCOUVER" );
1 row created.
SQL> insert into course_schedule values ("OAU",date "1999-08-10",2,"CHICAGO");
1 row created.
SQL> insert into course_schedule values ("SQL",date "1999-10-04",3,"SEATTLE");
1 row created.
SQL> insert into course_schedule values ("SQL",date "1999-12-13",4,"DALLAS" );
1 row created.
SQL> insert into course_schedule values ("JAV",date "1999-12-13",5,"SEATTLE");
1 row created.
SQL> insert into course_schedule values ("XML",date "2000-02-03",6,"VANCOUVER" );
1 row created.
SQL> insert into course_schedule values ("JAV",date "2000-02-01",7,"DALLAS" );
1 row created.
SQL> insert into course_schedule values ("PLS",date "2000-09-11",8,"VANCOUVER" );
1 row created.
SQL> insert into course_schedule values ("XML",date "2000-09-18",NULL,"SEATTLE");
1 row created.
SQL> insert into course_schedule values ("OAU",date "2000-09-27",9,"DALLAS" );
1 row created.
SQL> insert into course_schedule values ("ERM",date "2001-01-15",10, NULL );
1 row created.
SQL> insert into course_schedule values ("PRO",date "2001-02-19",NULL,"VANCOUVER" );
1 row created.
SQL> insert into course_schedule values ("RSD",date "2001-02-24",8,"CHICAGO");
1 row created.
SQL>
SQL>
SQL> create table registrations
2 ( attendee NUMBER(4)
3 , course VARCHAR2(6)
4 , begindate DATE
5 , evaluation NUMBER(1)) ;
Table created.
SQL>
SQL>
SQL> insert into registrations values (1, "SQL",date "1999-04-12",4 );
1 row created.
SQL> insert into registrations values (2, "SQL",date "1999-12-13",NULL);
1 row created.
SQL> insert into registrations values (3, "SQL",date "1999-12-13",NULL);
1 row created.
SQL> insert into registrations values (4, "OAU",date "1999-08-10",4 );
1 row created.
SQL> insert into registrations values (5, "OAU",date "2000-09-27",5 );
1 row created.
SQL> insert into registrations values (6, "JAV",date "1999-12-13",2 );
1 row created.
SQL> insert into registrations values (7, "JAV",date "2000-02-01",4 );
1 row created.
SQL> insert into registrations values (8, "JAV",date "2000-02-01",5 );
1 row created.
SQL> insert into registrations values (9, "XML",date "2000-02-03",4 );
1 row created.
SQL> insert into registrations values (10,"XML",date "2000-02-03",5 );
1 row created.
SQL> insert into registrations values (1, "PLS",date "2000-09-11",NULL);
1 row created.
SQL> insert into registrations values (2, "PLS",date "2000-09-11",NULL);
1 row created.
SQL> insert into registrations values (3, "PLS",date "2000-09-11",NULL);
1 row created.
SQL>
SQL>
SQL>
SQL> select o.trainer, avg(r.evaluation)
2 from course_schedule o
3 join
4 registrations r
5 using (course,begindate)
6 group by o.trainer;
TRAINER AVG(R.EVALUATION)
---------- -----------------
1 4
6 4.5
2 4
4
5 2
8
7 4.5
9 5
8 rows selected.
SQL>
SQL> drop table course_schedule;
Table dropped.
SQL>
SQL> drop table registrations;
Table dropped.
SQL>
SQL></source>

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