Oracle PL/SQL Tutorial/Table Joins/Introduction
Содержание
autotrace ansi full outer join
<source lang="sql">
SQL> SQL> SQL> create table myTable as
2 select "myTable" as C1 3 ,OBJECT_NAME 4 ,SUBOBJECT_NAME 5 ,OBJECT_ID 6 ,DATA_OBJECT_ID 7 ,OBJECT_TYPE 8 ,CREATED 9 ,LAST_DDL_TIME 10 ,TIMESTAMP 11 ,STATUS 12 ,TEMPORARY 13 ,GENERATED 14 ,SECONDARY 15 from dba_objects;
Table created. SQL> SQL> create table myTable2 as
2 select "myTable2" as C1 3 ,OBJECT_NAME || "myTable2" as object_name 4 ,SUBOBJECT_NAME 5 ,OBJECT_ID 6 ,DATA_OBJECT_ID 7 ,OBJECT_TYPE 8 ,CREATED 9 ,LAST_DDL_TIME 10 ,TIMESTAMP 11 ,STATUS 12 ,TEMPORARY 13 ,GENERATED 14 ,SECONDARY 15 from dba_objects 16 where rownum <= 10000;
Table created. SQL> SQL> create index myTable_object_id on myTable (object_id); Index created. SQL> SQL> create index myTable2_object_id on myTable2 (object_id); Index created. SQL> SQL> analyze table myTable compute statistics; Table analyzed. SQL> SQL> analyze table myTable2 compute statistics; Table analyzed. SQL> SQL> set autotrace TRACEONLY SQL> set timing on SQL> select *
2 from myTable a, myTable2 b 3 where a.object_id = b.object_id(+) 4 union 5 select * 6 from myTable a, myTable2 b 7 where a.object_id(+) = b.object_id;
13158 rows selected. Elapsed: 00:00:00.62 Execution Plan
Plan hash value: 4186416997
| Id | Operation | Name | Rows | Bytes |TempSpc| Cost |
| 0 | SELECT STATEMENT | | 23158 | 4296K| | 47039 | | 1 | SORT UNIQUE | | 23158 | 4296K| 10M| 47039 | | 2 | UNION-ALL | | | | | | | 3 | NESTED LOOPS OUTER | | 13158 | 2441K| | 26343 | | 4 | TABLE ACCESS FULL | MYTABLE | 13158 | 1169K| | 27 | | 5 | TABLE ACCESS BY INDEX ROWID| MYTABLE2 | 1 | 99 | | 2 | |* 6 | INDEX RANGE SCAN | MYTABLE2_OBJECT_ID | 1 | | | 1 | | 7 | NESTED LOOPS OUTER | | 10000 | 1855K| | 20022 | | 8 | TABLE ACCESS FULL | MYTABLE2 | 10000 | 966K| | 22 | | 9 | TABLE ACCESS BY INDEX ROWID| MYTABLE | 1 | 91 | | 2 | |* 10 | INDEX RANGE SCAN | MYTABLE_OBJECT_ID | 1 | | | 1 |
Predicate Information (identified by operation id):
6 - access("A"."OBJECT_ID"="B"."OBJECT_ID"(+))
10 - access("A"."OBJECT_ID"(+)="B"."OBJECT_ID")
Note
- cpu costing is off (consider enabling it)
Statistics
1 recursive calls
0 db block gets
43520 consistent gets
0 physical reads
0 redo size
1301014 bytes sent via SQL*Net to client
10027 bytes received via SQL*Net from client
879 SQL*Net roundtrips to/from client
1 sorts (memory)
0 sorts (disk)
13158 rows processed
SQL> SQL> SQL> select *
2 from myTable a full outer join myTable2 b 3 using (object_id);
13158 rows selected. Elapsed: 00:00:00.52 Execution Plan
Plan hash value: 3236823177
| Id | Operation | Name | Rows | Bytes | Cost |
| 0 | SELECT STATEMENT | | 13658 | 4401K| 26365 | | 1 | VIEW | | 13658 | 4401K| 26365 | | 2 | UNION-ALL | | | | | | 3 | NESTED LOOPS OUTER | | 13158 | 2441K| 26343 | | 4 | TABLE ACCESS FULL | MYTABLE | 13158 | 1169K| 27 | | 5 | TABLE ACCESS BY INDEX ROWID| MYTABLE2 | 1 | 99 | 2 | |* 6 | INDEX RANGE SCAN | MYTABLE2_OBJECT_ID | 1 | | 1 | |* 7 | FILTER | | | | | | 8 | TABLE ACCESS FULL | MYTABLE2 | 500 | 49500 | 22 | |* 9 | INDEX RANGE SCAN | MYTABLE_OBJECT_ID | 1 | 13 | 1 |
Predicate Information (identified by operation id):
6 - access("A"."OBJECT_ID"="B"."OBJECT_ID"(+))
7 - filter( NOT EXISTS (SELECT /*+ UNNEST */ 0 FROM "MYTABLE" "A" WHERE
"A"."OBJECT_ID"=:B1))
9 - access("A"."OBJECT_ID"=:B1)
Note
- cpu costing is off (consider enabling it)
Statistics
1 recursive calls
0 db block gets
45912 consistent gets
0 physical reads
0 redo size
956084 bytes sent via SQL*Net to client
10027 bytes received via SQL*Net from client
879 SQL*Net roundtrips to/from client
0 sorts (memory)
0 sorts (disk)
13158 rows processed
SQL> SQL> set timing off SQL> set autotrace off SQL> SQL> SQL> drop table myTable; Table dropped. SQL> SQL> drop table myTable2; Table dropped.</source>
Convert subqueries to JOINs
<source lang="sql">
SQL> SQL> CREATE TABLE emps (
2 emp varchar(30) 3 ,title varchar(30) 4 );
Table created. SQL> SQL> INSERT INTO emps VALUES ("Tom","Programmer"); 1 row created. SQL> INSERT INTO emps VALUES ("Jack","Tester"); 1 row created. SQL> INSERT INTO emps VALUES ("Mary","Technician"); 1 row created. SQL> SQL> CREATE TABLE JobLevel (
2 title varchar(30) 3 ,rank varchar(30) 4 );
Table created. SQL> SQL> INSERT INTO JobLevel VALUES ("Programmer","Level1"); 1 row created. SQL> INSERT INTO JobLevel VALUES ("Tester","Level2"); 1 row created. SQL> INSERT INTO JobLevel VALUES ("Technician","Level3"); 1 row created. SQL> SQL> CREATE TABLE salary (
2 rank varchar(30) 3 ,payment DECIMAL(10,2) 4 );
Table created. SQL> SQL> INSERT INTO salary VALUES ("Level1",2000.00); 1 row created. SQL> INSERT INTO salary VALUES ("Level2",3000.00); 1 row created. SQL> INSERT INTO salary VALUES ("Level3",5000.00); 1 row created. SQL> INSERT INTO salary VALUES ("Level4",6000.00); 1 row created. SQL> SQL> select * from emps;
EMP
TITLE
Tom Programmer Jack Tester Mary Technician 3 rows selected. SQL> select * from JobLevel;
TITLE
RANK
Programmer Level1 Tester Level2 Technician Level3
3 rows selected. SQL> select * from salary;
RANK PAYMENT
----------
Level1 2000 Level2 3000 Level3 5000 Level4 6000
4 rows selected. SQL> SQL> SELECT payment FROM salary WHERE rank =
2 (SELECT rank FROM JobLevel WHERE title = 3 (SELECT title FROM emps WHERE emp = "Jack"));
PAYMENT
3000
1 row selected. SQL> SQL> SQL> SQL> DROP TABLE emps; Table dropped. SQL> DROP TABLE JobLevel; Table dropped. SQL> DROP TABLE salary; Table dropped. SQL></source>
Example simple join.
<source lang="sql">
SQL> SQL> SQL> CREATE TABLE EMP (EMPNO NUMBER(4) NOT NULL,
2 ENAME VARCHAR2(10), 3 JOB VARCHAR2(9), 4 MGR NUMBER(4), 5 HIREDATE DATE, 6 SAL NUMBER(7, 2), 7 COMM NUMBER(7, 2), 8 DEPTNO NUMBER(2));
Table created. SQL> SQL> INSERT INTO EMP VALUES (7369, "SMITH", "CLERK", 7902, TO_DATE("17-DEC-1980", "DD-MON-YYYY"), 800, NULL, 20); 1 row created. SQL> INSERT INTO EMP VALUES (7499, "ALLEN", "SALESMAN", 7698, TO_DATE("20-FEB-1981", "DD-MON-YYYY"), 1600, 300, 30); 1 row created. SQL> INSERT INTO EMP VALUES (7521, "WARD", "SALESMAN", 7698, TO_DATE("22-FEB-1981", "DD-MON-YYYY"), 1250, 500, 30); 1 row created. SQL> INSERT INTO EMP VALUES (7566, "JONES", "MANAGER", 7839, TO_DATE("2-APR-1981", "DD-MON-YYYY"), 2975, NULL, 20); 1 row created. SQL> INSERT INTO EMP VALUES (7654, "MARTIN", "SALESMAN", 7698,TO_DATE("28-SEP-1981", "DD-MON-YYYY"), 1250, 1400, 30); 1 row created. SQL> INSERT INTO EMP VALUES (7698, "BLAKE", "MANAGER", 7839,TO_DATE("1-MAY-1981", "DD-MON-YYYY"), 2850, NULL, 30); 1 row created. SQL> INSERT INTO EMP VALUES (7782, "CLARK", "MANAGER", 7839,TO_DATE("9-JUN-1981", "DD-MON-YYYY"), 2450, NULL, 10); 1 row created. SQL> INSERT INTO EMP VALUES (7788, "SCOTT", "ANALYST", 7566,TO_DATE("09-DEC-1982", "DD-MON-YYYY"), 3000, NULL, 20); 1 row created. SQL> INSERT INTO EMP VALUES (7839, "KING", "PRESIDENT", NULL,TO_DATE("17-NOV-1981", "DD-MON-YYYY"), 5000, NULL, 10); 1 row created. SQL> INSERT INTO EMP VALUES (7844, "TURNER", "SALESMAN", 7698,TO_DATE("8-SEP-1981", "DD-MON-YYYY"), 1500, 0, 30); 1 row created. SQL> INSERT INTO EMP VALUES (7876, "ADAMS", "CLERK", 7788,TO_DATE("12-JAN-1983", "DD-MON-YYYY"), 1100, NULL, 20); 1 row created. SQL> INSERT INTO EMP VALUES (7900, "JAMES", "CLERK", 7698,TO_DATE("3-DEC-1981", "DD-MON-YYYY"), 950, NULL, 30); 1 row created. SQL> INSERT INTO EMP VALUES (7902, "FORD", "ANALYST", 7566,TO_DATE("3-DEC-1981", "DD-MON-YYYY"), 3000, NULL, 20); 1 row created. SQL> INSERT INTO EMP VALUES (7934, "MILLER", "CLERK", 7782,TO_DATE("23-JAN-1982", "DD-MON-YYYY"), 1300, NULL, 10); 1 row created. SQL> SQL> CREATE TABLE DEPT (DEPTNO NUMBER(2),DNAME VARCHAR2(14),LOC VARCHAR2(13) ); Table created. SQL> SQL> INSERT INTO DEPT VALUES (10, "ACCOUNTING", "NEW YORK"); 1 row created. SQL> INSERT INTO DEPT VALUES (20, "RESEARCH", "DALLAS"); 1 row created. SQL> INSERT INTO DEPT VALUES (30, "SALES", "CHICAGO"); 1 row created. SQL> INSERT INTO DEPT VALUES (40, "OPERATIONS", "BOSTON"); 1 row created. SQL> SQL> select * from emp;
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- --------- ---------- --------- ---------- ---------- ----------
7369 SMITH CLERK 7902 17-DEC-80 800 20
7499 ALLEN SALESMAN 7698 20-FEB-81 1600 300 30
7521 WARD SALESMAN 7698 22-FEB-81 1250 500 30
7566 JONES MANAGER 7839 02-APR-81 2975 20
7654 MARTIN SALESMAN 7698 28-SEP-81 1250 1400 30
7698 BLAKE MANAGER 7839 01-MAY-81 2850 30
7782 CLARK MANAGER 7839 09-JUN-81 2450 10
7788 SCOTT ANALYST 7566 09-DEC-82 3000 20
7839 KING PRESIDENT 17-NOV-81 5000 10
7844 TURNER SALESMAN 7698 08-SEP-81 1500 0 30
7876 ADAMS CLERK 7788 12-JAN-83 1100 20
7900 JAMES CLERK 7698 03-DEC-81 950 30
7902 FORD ANALYST 7566 03-DEC-81 3000 20
7934 MILLER CLERK 7782 23-JAN-82 1300 10
14 rows selected. SQL> select * from dept;
DEPTNO DNAME LOC
-------------- -------------
10 ACCOUNTING NEW YORK
20 RESEARCH DALLAS
30 SALES CHICAGO
40 OPERATIONS BOSTON
SQL> SQL> SQL> select d.deptno, d.dname, e.empno, e.sal, e.rum
2 from dept d, emp e 3 where d.deptno=e.deptno; DEPTNO DNAME EMPNO SAL COMM
-------------- ---------- ---------- ----------
20 RESEARCH 7369 800
30 SALES 7499 1600 300
30 SALES 7521 1250 500
20 RESEARCH 7566 2975
30 SALES 7654 1250 1400
30 SALES 7698 2850
10 ACCOUNTING 7782 2450
20 RESEARCH 7788 3000
10 ACCOUNTING 7839 5000
30 SALES 7844 1500 0
20 RESEARCH 7876 1100
30 SALES 7900 950
20 RESEARCH 7902 3000
10 ACCOUNTING 7934 1300
14 rows selected. SQL> SQL> drop table emp; Table dropped. SQL> SQL> drop table dept; Table dropped. SQL></source>
Performing SELECT Statements that Use More than Two Tables
Joins can be used to connect any number of tables.
The number of joins you will need in your WHERE clause is total_number_of_tables - 1
There are two types of join conditions, which are based on the operator.
Equijoins - You use the equality operator (=) in the join.
Non-equijoins - You use an operator other than equals in the join, such as <, >, BETWEEN, and so on.
7. 1. Introduction 7. 1. 1. Performing SELECT Statements that Use More than Two Tables 7. 1. 2. <A href="/Tutorial/Oracle/0140__Table-Joins/Threedifferenttypesofjoins.htm">Three different types of joins:</a> 7. 1. 3. <A href="/Tutorial/Oracle/0140__Table-Joins/UnderstandingNonequijoins.htm">Understanding Non-equijoins</a> 7. 1. 4. <A href="/Tutorial/Oracle/0140__Table-Joins/PerformingSELECTStatementsthatUseTwoTables.htm">Performing SELECT Statements that Use Two Tables</a> 7. 1. 5. <A href="/Tutorial/Oracle/0140__Table-Joins/Examplesimplejoin.htm">Example simple join.</a> 7. 1. 6. <A href="/Tutorial/Oracle/0140__Table-Joins/Usetablealiasintablejoin.htm">Use table alias in table join</a> 7. 1. 7. <A href="/Tutorial/Oracle/0140__Table-Joins/ConvertsubqueriestoJOINs.htm">Convert subqueries to JOINs</a> 7. 1. 8. <A href="/Tutorial/Oracle/0140__Table-Joins/autotraceansifullouterjoin.htm">autotrace ansi full outer join</a>
Performing SELECT Statements that Use Two Tables
To join two tables means that you specify both the tables in the query"s FROM clause.
And Use related columns from each table.
The related columns could be a foreign key from one table and the primary key from another table.
You use an operator, such as the equality operator (=), in the query"s WHERE 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 ) 9 /
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)
2 values (1, "Jason", to_date("19960725","YYYYMMDD"), 1234, 8767, "E")
3 /
1 row created. SQL> insert into Employee(EMPNO, EName, HIREDATE, ORIG_SALARY, CURR_SALARY, REGION)
2 values (2, "John", to_date("19970715","YYYYMMDD"), 2341, 3456, "W")
3 /
1 row created. SQL> insert into Employee(EMPNO, EName, HIREDATE, ORIG_SALARY, CURR_SALARY, REGION)
2 values (3, "Joe", to_date("19860125","YYYYMMDD"), 4321, 5654, "E")
3 /
1 row created. SQL> insert into Employee(EMPNO, EName, HIREDATE, ORIG_SALARY, CURR_SALARY, REGION)
2 values (4, "Tom", to_date("20060913","YYYYMMDD"), 2413, 6787, "W")
3 /
1 row created. SQL> insert into Employee(EMPNO, EName, HIREDATE, ORIG_SALARY, CURR_SALARY, REGION)
2 values (5, "Jane", to_date("20050417","YYYYMMDD"), 7654, 4345, "E")
3 /
1 row created. SQL> insert into Employee(EMPNO, EName, HIREDATE, ORIG_SALARY, CURR_SALARY, REGION)
2 values (6, "James", to_date("20040718","YYYYMMDD"), 5679, 6546, "W")
3 /
1 row created. SQL> insert into Employee(EMPNO, EName, HIREDATE, ORIG_SALARY, CURR_SALARY, REGION)
2 values (7, "Jodd", to_date("20030720","YYYYMMDD"), 5438, 7658, "E")
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
--------------- --------- ----------- ----------- -
1 Jason 25-JUL-96 1234 8767 E
2 John 15-JUL-97 2341 3456 W
3 Joe 25-JAN-86 4321 5654 E
4 Tom 13-SEP-06 2413 6787 W
5 Jane 17-APR-05 7654 4345 E
6 James 18-JUL-04 5679 6546 W
7 Jodd 20-JUL-03 5438 7658 E
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> SQL> SELECT employee.ename, job.jobtitle
2 FROM employee, job 3 WHERE employee.empno = job.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>
Three different types of joins:
Inner joins - Return a row only when the columns in the join contain values that satisfy the join condition.
This means that if a row has a null value in one of the columns in the join condition, that row isn"t returned.
Outer joins - Can return a row even when one of the columns in the join condition contains a null value.
Self joins - Return rows joined on the same table.
7. 1. Introduction 7. 1. 1. <A href="/Tutorial/Oracle/0140__Table-Joins/PerformingSELECTStatementsthatUseMorethanTwoTables.htm">Performing SELECT Statements that Use More than Two Tables</a> 7. 1. 2. Three different types of joins: 7. 1. 3. <A href="/Tutorial/Oracle/0140__Table-Joins/UnderstandingNonequijoins.htm">Understanding Non-equijoins</a> 7. 1. 4. <A href="/Tutorial/Oracle/0140__Table-Joins/PerformingSELECTStatementsthatUseTwoTables.htm">Performing SELECT Statements that Use Two Tables</a> 7. 1. 5. <A href="/Tutorial/Oracle/0140__Table-Joins/Examplesimplejoin.htm">Example simple join.</a> 7. 1. 6. <A href="/Tutorial/Oracle/0140__Table-Joins/Usetablealiasintablejoin.htm">Use table alias in table join</a> 7. 1. 7. <A href="/Tutorial/Oracle/0140__Table-Joins/ConvertsubqueriestoJOINs.htm">Convert subqueries to JOINs</a> 7. 1. 8. <A href="/Tutorial/Oracle/0140__Table-Joins/autotraceansifullouterjoin.htm">autotrace ansi full outer join</a>
Understanding Non-equijoins
A non-equijoin uses an operator other than the equality operator in the join.
Examples of non-equality operators are:
- not-equal (<>),
- less than (<),
- greater than (>),
- less than or equal to (<=),
- greater than or equal to (>=),
- LIKE,
- IN, and
- BETWEEN.
7. 1. Introduction 7. 1. 1. <A href="/Tutorial/Oracle/0140__Table-Joins/PerformingSELECTStatementsthatUseMorethanTwoTables.htm">Performing SELECT Statements that Use More than Two Tables</a> 7. 1. 2. <A href="/Tutorial/Oracle/0140__Table-Joins/Threedifferenttypesofjoins.htm">Three different types of joins:</a> 7. 1. 3. Understanding Non-equijoins 7. 1. 4. <A href="/Tutorial/Oracle/0140__Table-Joins/PerformingSELECTStatementsthatUseTwoTables.htm">Performing SELECT Statements that Use Two Tables</a> 7. 1. 5. <A href="/Tutorial/Oracle/0140__Table-Joins/Examplesimplejoin.htm">Example simple join.</a> 7. 1. 6. <A href="/Tutorial/Oracle/0140__Table-Joins/Usetablealiasintablejoin.htm">Use table alias in table join</a> 7. 1. 7. <A href="/Tutorial/Oracle/0140__Table-Joins/ConvertsubqueriestoJOINs.htm">Convert subqueries to JOINs</a> 7. 1. 8. <A href="/Tutorial/Oracle/0140__Table-Joins/autotraceansifullouterjoin.htm">autotrace ansi full outer join</a>
Use table alias in table join
<source lang="sql">
SQL> SQL> CREATE TABLE employee (
2 id number, 3 name varchar(100), 4 birth_date date, 5 gender varchar2(30) );
Table created. SQL> SQL> CREATE TABLE employee_evaluation (
2 id number, 3 title varchar2(100), 4 written_date date );
Table created. SQL> SQL> SQL> SELECT a.id,
2 a.name, 3 p.title, 4 p.written_date 5 FROM employee a, 6 employee_evaluation p 7 WHERE a.id = p.id 8 ORDER BY a.name, 9 p.written_date, 10 p.title;
no rows selected SQL> SQL> drop table employee; Table dropped. SQL> SQL> drop table employee_evaluation; Table dropped.</source>
