Oracle PL/SQL Tutorial/Query Select/Hierarchical Queries
Содержание
- 1 Add where clause to a Hierarchical Query
- 2 Eliminating Nodes and Branches from a Hierarchical Query
- 3 employee tree: who is my manager
- 4 Formatting the Results from a Hierarchical Query
- 5 Hierarchical Queries
- 6 Output full path of hierarchy
- 7 pseudocolumn LEVEL and an example of using the levels.
- 8 pseudocolumn LEVEL and an example of using the levels with an update.
- 9 Starting at a node other than the root
- 10 sys_connect_by_path
- 11 Traversing Upward Through the Tree
- 12 Using the CONNECT BY and START WITH Clauses
Add where clause to a Hierarchical Query
<source lang="sql">
SQL> SQL> 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 LEVEL,
2 LPAD(" ", 2 * LEVEL - 1) || ename
3 FROM employee
4 WHERE salary <= 50000
5 START WITH empno = 1
6 CONNECT BY PRIOR empno = manager_id;
WHERE salary <= 50000
*
ERROR at line 4: ORA-00904: "SALARY": invalid identifier
SQL> SQL> SQL> -- clean the table SQL> drop table Employee
2 /
Table dropped. SQL> drop table job
2 /
Table dropped. SQL></source>
Eliminating Nodes and Branches from a Hierarchical Query
<source lang="sql">
SQL> SQL> SQL> 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 LEVEL,
2 LPAD(" ", 2 * LEVEL - 1) || ename
3 FROM employee
4 WHERE ename != "James"
5 START WITH empno = 1
6 CONNECT BY PRIOR empno = manager_id;
LEVEL LPAD("",2*LEVEL-1)||ENAME
1 Jason
SQL> SQL> -- clean the table SQL> drop table Employee
2 /
Table dropped. SQL> drop table job
2 /
Table dropped. SQL> SQL></source>
employee tree: who is my manager
<source lang="sql">
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", "TRAINER", 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", "TRAINER", 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", "TRAINER", 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", "TRAINER", 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> SQL> select lpad(" ",2*level-1)||ename as ename
2 from emp 3 start with mgr is null 4 connect by nocycle prior empno = mgr;
ENAME
Peter
Jane
Smart
Ana
Fake
Tom
Black
Jack
Wil
Mary
Take
Jane
Chris
Mike
14 rows selected. SQL> SQL> SQL> drop table emp; Table dropped.</source>
Formatting the Results from a Hierarchical Query
<source lang="sql">
SQL> SQL> 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> SET PAGESIZE 999 SQL> COLUMN employe FORMAT A25 SQL> SELECT LEVEL,
2 LPAD(" ", 2 * LEVEL - 1) || ename
3 FROM employee
4 START WITH empno = 1
5 CONNECT BY PRIOR empno= manager_id;
LEVEL
LPAD("",2*LEVEL-1)||ENAME
1 Jason
SQL> SQL> SQL> clear columns; columns cleared SQL> SQL> -- clean the table SQL> drop table Employee
2 /
Table dropped. SQL> drop table job
2 /
Table dropped. SQL> SQL></source>
Hierarchical Queries
Using the CONNECT BY and START WITH Clauses
The syntax for the CONNECT BY and START WITH clauses of a SELECT statement is as follows:
<source lang="sql">
SELECT [LEVEL], column, expression, ... FROM table [WHERE where_clause] [[START WITH start_condition] [CONNECT BY PRIOR prior_condition]];</source>
where
- LEVEL is a pseudo-column that tells you how far into a tree you are.
- LEVEL returns 1 for a root node, 2 for a child of the root, and so on.
- start_condition specifies where to start the hierarchical query from.
- You must specify a START WITH clause when writing a hierarchical query.
- An example start_condition is employee_id = 1, which specifies the query starts from employee #1.
- prior_condition specifies the relationship between the parent and child rows.
- You must specify a CONNECT BY PRIOR clause when writing a hierarchical query.
An example prior_condition is employee_id = manager_id, which specifies the relationship is between the parent employee_id and the child manager_id-that is, the child"s manager_id points to the parent"s employee_id.
Quote from:
Oracle Database 10g SQL (Osborne ORACLE Press Series) (Paperback)
# Paperback: 608 pages
# Publisher: McGraw-Hill Osborne Media; 1st edition (February 20, 2004)
# Language: English
# ISBN-10: 0072229810
# ISBN-13: 978-0072229813
Output full path of hierarchy
<source lang="sql">
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", "TRAINER", 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", "TRAINER", 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", "TRAINER", 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", "TRAINER", 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> SQL> column full_path format a40 SQL> SQL> select ename
2 , connect_by_root ename as Designer 3 , sys_connect_by_path(ename," > ") as full_path 4 from emp 5 start with job = "Designer" 6 connect by prior empno = mgr;
ENAME DESIGNER FULL_PATH
-------- ----------------------------------------
Jane Jane > Jane Smart Jane > Jane > Smart Ana Jane > Jane > Smart > Ana Fake Jane > Jane > Fake Tom Jane > Jane > Fake > Tom Black Black > Black Jack Black > Black > Jack Wil Black > Black > Wil Mary Black > Black > Mary Take Black > Black > Take Jane Black > Black > Jane Chris Chris > Chris Mike Chris > Chris > Mike Peter Peter > Peter Jane Peter > Peter > Jane Smart Peter > Peter > Jane > Smart Ana Peter > Peter > Jane > Smart > Ana Fake Peter > Peter > Jane > Fake Tom Peter > Peter > Jane > Fake > Tom ENAME DESIGNER FULL_PATH
-------- ----------------------------------------
Black Peter > Peter > Black Jack Peter > Peter > Black > Jack Wil Peter > Peter > Black > Wil Mary Peter > Peter > Black > Mary Take Peter > Peter > Black > Take Jane Peter > Peter > Black > Jane Chris Peter > Peter > Chris Mike Peter > Peter > Chris > Mike 27 rows selected. SQL> SQL> SQL> drop table emp; Table dropped.</source>
pseudocolumn LEVEL and an example of using the levels.
<source lang="sql">
SQL> SQL> CREATE TABLE book (
2 isbn VARCHAR2(10) PRIMARY KEY, 3 parent_isbn VARCHAR2(10), 4 series VARCHAR2(20), 5 category VARCHAR2(20), 6 title VARCHAR2(100), 7 num_pages NUMBER, 8 price NUMBER, 9 copyright NUMBER(4));
Table created. SQL> SQL> INSERT INTO book (isbn, parent_isbn, series, category, title, num_pages, price, copyright)
2 VALUES ("1", "2", "Oracle", "Oracle Server", "SQL", 664, 49.99, 2002);
1 row created. SQL> SQL> INSERT INTO book (isbn, parent_isbn, series, category, title, num_pages, price, copyright)
2 VALUES ("2", null, "Oracle", "Oracle Server", "Java", 772, 49.99, 2000);
1 row created. SQL> SQL> INSERT INTO book (isbn, parent_isbn, series, category, title, num_pages, price, copyright)
2 VALUES ("3", "1", "Oracle", "Oracle Server", "XML", 1008, 54.99, 2004);
1 row created. SQL> SQL> SET SERVEROUTPUT ON SQL> SQL> DECLARE
2 v_level PLS_INTEGER; 3 v_title book.TITLE%TYPE; 4 CURSOR cur_tree IS SELECT isbn, title, series FROM book; 5 BEGIN 6 FOR l IN cur_tree 7 LOOP 8 SELECT max(LEVEL) INTO v_level FROM book 9 START WITH isbn = l.isbn 10 CONNECT BY PRIOR parent_isbn = isbn; 11 12 DBMS_OUTPUT.PUT_LINE(l.title||" is book "||v_level||" in the "||l.series||" series"); 13 14 END LOOP; 15 CLOSE cur_tree; 16 EXCEPTION 17 WHEN OTHERS 18 THEN 19 DBMS_OUTPUT.PUT_LINE(sqlerrm); 20 END; 21 /
SQL is book 2 in the Oracle series Java is book 1 in the Oracle series XML is book 3 in the Oracle series ORA-01001: invalid cursor PL/SQL procedure successfully completed. SQL> SQL> drop table book; Table dropped.</source>
pseudocolumn LEVEL and an example of using the levels with an update.
<source lang="sql">
SQL> SQL> SQL> CREATE TABLE book (
2 isbn VARCHAR2(10) PRIMARY KEY, 3 parent_isbn VARCHAR2(10), 4 series VARCHAR2(20), 5 category VARCHAR2(20), 6 title VARCHAR2(100), 7 num_pages NUMBER, 8 price NUMBER, 9 copyright NUMBER(4));
Table created. SQL> SQL> INSERT INTO book (isbn, parent_isbn, series, category, title, num_pages, price, copyright)
2 VALUES ("1", "2", "Oracle", "Oracle Server", "SQL", 664, 49.99, 2002);
1 row created. SQL> SQL> INSERT INTO book (isbn, parent_isbn, series, category, title, num_pages, price, copyright)
2 VALUES ("2", null, "Oracle", "Oracle Server", "Java", 772, 49.99, 2000);
1 row created. SQL> SQL> INSERT INTO book (isbn, parent_isbn, series, category, title, num_pages, price, copyright)
2 VALUES ("3", "1", "Oracle", "Oracle Server", "XML", 1008, 54.99, 2004);
1 row created. SQL> SQL> INSERT INTO book (isbn, parent_isbn, series, category, title, num_pages, price, copyright)
2 VALUES ("4", null, "Oracle Ebusiness", "Oracle Ebusiness", "Oracle E-Business Suite Financials Handbook", 820, 59.99, 2002);
1 row created. SQL> SQL> SQL> ALTER TABLE book
2 ADD position NUMBER(10);
Table altered. SQL> SQL> SQL> SET SERVEROUTPUT ON SQL> SQL> DECLARE
2 v_level PLS_INTEGER; 3 v_title book.TITLE%TYPE; 4 5 CURSOR cur_tree IS SELECT isbn, title, series FROM book; 6 BEGIN 7 8 FOR l IN cur_tree 9 LOOP 10 11 SELECT max(LEVEL) INTO v_level FROM book 12 START WITH isbn = l.isbn 13 CONNECT BY PRIOR parent_isbn = isbn; 14 15 UPDATE book SET position = v_level WHERE isbn = l.isbn; 16 17 END LOOP; 18 19 20 COMMIT; 21 22 EXCEPTION 23 WHEN OTHERS 24 THEN 25 DBMS_OUTPUT.PUT_LINE(sqlerrm); 26 END; 27 /
PL/SQL procedure successfully completed. SQL> SQL> SQL> SQL> SET PAGES 9999 SQL> SELECT title, position
2 FROM book 3 ORDER BY series, position;
TITLE
POSITION
Java
1
SQL
2
XML
3
Oracle E-Business Suite Financials Handbook
1
4 rows selected. SQL> SQL> SQL> INSERT INTO book (isbn, parent_isbn, series, category, title, num_pages, price, copyright)
2 VALUES ("111111", null, "Oracle", "Oracle Server", "Oracle8.0 PL/SQL Programming", 772, 49.99, 2000);
1 row created. SQL> SQL> UPDATE book
2 SET parent_isbn = "111111" 3 WHERE isbn = "2";
1 row updated. SQL> SQL> COMMIT; Commit complete. SQL> SQL> SQL> SELECT title, position
2 FROM book 3 ORDER BY series, position;
TITLE
POSITION
Java
1
SQL
2
XML
3
Oracle8.0 PL/SQL Programming
Oracle E-Business Suite Financials Handbook
1
5 rows selected. SQL></source>
Starting at a node other than the root
<source lang="sql">
SQL> SQL> SQL> 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 LEVEL, LPAD(" ", 2 * LEVEL - 1) || ename
2 FROM employee
3 START WITH ename = "Jane"
4 CONNECT BY PRIOR empno = manager_id;
LEVEL LPAD("",2*LEVEL-1)||ENAME
1 Jane
2 James
3 Jodd
SQL> SQL> -- clean the table SQL> drop table Employee
2 /
Table dropped. SQL> drop table job
2 /
Table dropped. SQL> SQL></source>
sys_connect_by_path
<source lang="sql">
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", "TRAINER", 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", "TRAINER", 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", "TRAINER", 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", "TRAINER", 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> SQL> SQL> select ename
2 , sys_connect_by_path(ename,"|") as path 3 from emp 4 start with mgr is null 5 connect by prior empno = mgr 6 order siblings by ename;
ENAME
PATH
Peter |Peter Black |Peter|Black Jack |Peter|Black|Jack Jane |Peter|Black|Jane Mary |Peter|Black|Mary Take |Peter|Black|Take ENAME
PATH
Wil |Peter|Black|Wil Chris |Peter|Chris Mike |Peter|Chris|Mike Jane |Peter|Jane Fake |Peter|Jane|Fake Tom ENAME
PATH
|Peter|Jane|Fake|Tom Smart |Peter|Jane|Smart Ana |Peter|Jane|Smart|Ana
14 rows selected. SQL> / ENAME
PATH
Peter |Peter Black |Peter|Black Jack |Peter|Black|Jack Jane |Peter|Black|Jane Mary |Peter|Black|Mary Take |Peter|Black|Take ENAME
PATH
Wil |Peter|Black|Wil Chris |Peter|Chris Mike |Peter|Chris|Mike Jane |Peter|Jane Fake |Peter|Jane|Fake Tom ENAME
PATH
|Peter|Jane|Fake|Tom Smart |Peter|Jane|Smart Ana |Peter|Jane|Smart|Ana
14 rows selected. SQL> SQL> SQL> drop table emp; Table dropped. SQL></source>
Traversing Upward Through the Tree
<source lang="sql">
SQL> SQL> SQL> 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 LEVEL,
2 LPAD(" ", 2 * LEVEL - 1) || ename
3 FROM employee
4 START WITH ename = "James"
5 CONNECT BY PRIOR manager_id = empno;
ERROR: ORA-01436: CONNECT BY loop in user data
no rows selected SQL> SQL> -- clean the table SQL> drop table Employee
2 /
Table dropped. SQL> drop table job
2 /
Table dropped. SQL> SQL></source>
Using the CONNECT BY and START WITH Clauses
<source lang="sql">
SQL> SQL> 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 empno, manager_id, ename
2 FROM employee
3 START WITH empno = 1
4 CONNECT BY PRIOR empno = manager_id;
EMPNO MANAGER_ID ENAME
---------- ---------------
1 2 Jason
SQL> SQL> SQL> SQL> -- clean the table SQL> drop table Employee
2 /
Table dropped. SQL> drop table job
2 /
Table dropped.</source>
