Oracle PL/SQL/Hierarchical Query/Level — различия между версиями

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Версия 13:45, 26 мая 2010

Browse Products with three level nested queries

 
SQL>
SQL> CREATE TABLE Product (
  2  ProductID INT NOT NULL PRIMARY KEY,
  3  Name VARCHAR(50) NOT NULL,
  4  Description VARCHAR(1000) NOT NULL,
  5  Price NUMBER NULL,
  6  ImagePath VARCHAR(50) NULL,
  7  soldout NUMBER(1,0) NULL,
  8  Promotion NUMBER(1,0) NULL);
Table created.
SQL>
SQL> CREATE SEQUENCE ProductIDSeq;
Sequence created.
SQL>
SQL> CREATE OR REPLACE TRIGGER ProductAutonumberTrigger
  2  BEFORE INSERT ON Product
  3  FOR EACH ROW
  4  BEGIN
  5     SELECT ProductIDSeq.NEXTVAL
  6     INTO :NEW.ProductID FROM DUAL;
  7  END;
  8  /
Trigger created.
SQL>
SQL> INSERT INTO Product (Name, Description, Price, ImagePath,soldout, Promotion)
  2  VALUES ("Pen", "Ball Pen",5.99, "pen.jpg", 1, 0);
1 row created.
SQL>
SQL> INSERT INTO Product (Name, Description, Price, ImagePath, soldout, Promotion)
  2  VALUES ("Ruler", "Long",14.99, "ruler.jpg", 0, 0);
1 row created.
SQL>
SQL> INSERT INTO Product (Name, Description, Price, ImagePath, soldout, Promotion)
  2  VALUES ("Desk", "Computer Desk",5.99, "desk.jpg", 0, 1);
1 row created.
SQL>
SQL> INSERT INTO Product (Name, Description, Price, ImagePath, soldout, Promotion)
  2  VALUES ("PC", "Notebook",49.99, "pc.jpg", 0, 1);
1 row created.
SQL>
SQL> INSERT INTO Product (Name, Description, Price, ImagePath, soldout, Promotion)
  2  VALUES ("Mouse", "Wireless",9.99, "mouse.jpg",  1, 0);
1 row created.
SQL>
SQL> INSERT INTO Product (Name, Description, Price, ImagePath, soldout, Promotion)
  2  VALUES ("Keyboard", "keyboard",3.75, "keyboard.jpg", 0, 0);
1 row created.
SQL>
SQL> SELECT ProductID, Name FROM
  2       (SELECT ProductID, Name, ROWNUM AS rn FROM
  3            (SELECT ProductID, Name
  4             FROM Product
  5             ORDER BY ProductID)
  6       ) inner
  7  WHERE inner.rn BETWEEN 6 AND 10;
 PRODUCTID NAME
---------- --------------------------------------------------
         6 Keyboard
1 row selected.
SQL>
SQL> drop table product;
Table dropped.
SQL> drop sequence ProductIDSeq;
Sequence dropped.



pseudocolumn LEVEL and an example of using the levels.

 
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.



pseudocolumn LEVEL and an example of using the levels with an update.

 
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>



sort by LEVEL

  
SQL>
SQL> create table employee(
  2           emp_no                 integer         primary key
  3          ,lastname               varchar2(20)    not null
  4          ,firstname              varchar2(15)    not null
  5          ,midinit                varchar2(1)
  6          ,street                 varchar2(30)
  7          ,city                   varchar2(20)
  8          ,state                  varchar2(2)
  9          ,zip                    varchar2(5)
 10          ,zip_4                  varchar2(4)
 11          ,area_code              varchar2(3)
 12          ,phone                  varchar2(8)
 13          ,salary                 number(3)
 14          ,birthdate              date
 15          ,hiredate               date
 16          ,title                  varchar2(20)
 17          ,dept_no                integer
 18          ,mgr                    integer
 19          ,region                 number
 20          ,division               number
 21          ,total_sales            number
 22  );
Table created.
SQL> insert into employee(emp_no, lastname, firstname, midinit, street, city, state, zip,zip_4, area_code, phone, salary, birthdate, hiredate,title, dept_no, mgr, region, division, total_sales)
  2               values (1,"Anderson","Nancy","N","33 Ave","London","NY","11111","1111","212","234-1111",3.75,"21-mar-1927","1-feb-1947","Sales Manager",2,null,100,10,40000);
1 row created.
SQL> insert into employee(emp_no, lastname, firstname, midinit, street, city, state, zip,zip_4, area_code, phone, salary, birthdate, hiredate,title, dept_no, mgr, region, division, total_sales)
  2               values (2,"Last","First","F","12 Ave","Paris","CA","22222","2222","221","867-2222",7.75,"14-feb-1976","15-mar-1985","Sales Clerk",2,1,100,10,10000);
1 row created.
SQL> insert into employee(emp_no, lastname, firstname, midinit, street, city, state, zip,zip_4, area_code, phone, salary, birthdate, hiredate,title, dept_no, mgr, region, division, total_sales)
  2               values (3,"Wash","Georgia","G","1 Street14","Barton","NJ","33333","3333","214","340-3333",11.50,"2-jul-1977","21-apr-2004","Designer",1,2,100,10,40000);
1 row created.
SQL> insert into employee(emp_no, lastname, firstname, midinit, street, city, state, zip,zip_4, area_code, phone, salary, birthdate, hiredate,title, dept_no, mgr, region, division, total_sales)
  2               values (4,"Bush","Dave","D","56 Street","Island","RI","44444","4444","215","777-4444",21.65,"15-may-1945","2-aug-1975","Designer",1,2,100,10,40000);
1 row created.
SQL> insert into employee(emp_no, lastname, firstname, midinit, street, city, state, zip,zip_4, area_code, phone, salary, birthdate, hiredate,title, dept_no, mgr, region, division, total_sales)
  2               values (5,"Will","Robin","W","56 Street","Island","MA","55555","5555","216","777-5555",24.65,"10-dec-1980","2-aug-2007","Designer",1,5,100,10,40000);
1 row created.
SQL> insert into employee(emp_no, lastname, firstname, midinit, street, city, state, zip,zip_4, area_code, phone, salary, birthdate, hiredate,title, dept_no, mgr, region, division, total_sales)
  2               values (6,"Pete","Mona","M","13 Ave","York","MO","66666","6666","217","111-6666",9,"14-feb-1966","15-mar-1985","Sales Clerk",2,5,100,10,40000);
1 row created.
SQL> insert into employee(emp_no, lastname, firstname, midinit, street, city, state, zip,zip_4, area_code, phone, salary, birthdate, hiredate,title, dept_no, mgr, region, division, total_sales)
  2               values (7,"Roke","John","J","67 Ave","New York","BC","77777","7777","218","122-7777",10.00,"14-jun-1955","15-mar-1975","Accountant",3,2,100,10,40000);
1 row created.
SQL> insert into employee(emp_no, lastname, firstname, midinit, street, city, state, zip,zip_4, area_code, phone, salary, birthdate, hiredate,title, dept_no, mgr, region, division, total_sales)
  2               values (8,"Horry","Tedi","T","1236 Lane","Newton","NY","88888","8888","219","222-8888",13.00,"10-jun-1955","15-aug-1985","Sales Representative",3,2,100,10,50000);
1 row created.
SQL> insert into employee(emp_no, lastname, firstname, midinit, street, city, state, zip,zip_4, area_code, phone, salary, birthdate, hiredate,title, dept_no, mgr, region, division, total_sales)
  2                values (9,"Bar","Candi","C","400 East Street","Yorken","NY","99999","9999","220","321-9999",12.00,"10-oct-1933","15-jan-1969","Sales Representative",3,5,100,10,35000);
1 row created.
SQL>
SQL> select * from employee;
    EMP_NO LASTNAME             FIRSTNAME       M STREET                         CITY                 ST ZIP   ZIP_ ARE PHONE        SALARY
---------- -------------------- --------------- - ------------------------------ -------------------- -- ----- ---- --- -------- ----------
BIRTHDATE            HIREDATE             TITLE                   DEPT_NO        MGR     REGION   DIVISION TOTAL_SALES
-------------------- -------------------- -------------------- ---------- ---------- ---------- ---------- -----------
         1 Anderson             Nancy           N 33 Ave                         London               NY 11111 1111 212 234-1111          4
21-MAR-1927 00:00:00 01-FEB-1947 00:00:00 Sales Manager                 2                   100      10  40000
         2 Last                 First           F 12 Ave                         Paris                CA 22222 2222 221 867-2222          8
14-FEB-1976 00:00:00 15-MAR-1985 00:00:00 Sales Clerk                   2          1        100      10  10000
         3 Wash                 Georgia         G 1 Street14                     Barton               NJ 33333 3333 214 340-3333         12
02-JUL-1977 00:00:00 21-APR-2004 00:00:00 Designer                      1          2        100      10  40000
         4 Bush                 Dave            D 56 Street                      Island               RI 44444 4444 215 777-4444         22
15-MAY-1945 00:00:00 02-AUG-1975 00:00:00 Designer                      1          2        100      10  40000
         5 Will                 Robin           W 56 Street                      Island               MA 55555 5555 216 777-5555         25
10-DEC-1980 00:00:00 02-AUG-2007 00:00:00 Designer                      1          5        100      10  40000
         6 Pete                 Mona            M 13 Ave                         York                 MO 66666 6666 217 111-6666          9
14-FEB-1966 00:00:00 15-MAR-1985 00:00:00 Sales Clerk                   2          5        100      10  40000
         7 Roke                 John            J 67 Ave                         New York             BC 77777 7777 218 122-7777         10
14-JUN-1955 00:00:00 15-MAR-1975 00:00:00 Accountant                    3          2        100      10  40000
         8 Horry                Tedi            T 1236 Lane                      Newton               NY 88888 8888 219 222-8888         13
10-JUN-1955 00:00:00 15-AUG-1985 00:00:00 Sales Representative          3          2        100      10  50000
         9 Bar                  Candi           C 400 East Street                Yorken               NY 99999 9999 220 321-9999         12
10-OCT-1933 00:00:00 15-JAN-1969 00:00:00 Sales Representative          3          5        100      10  35000

9 rows selected.
SQL>
SQL> select lpad(" ",2*level-2) || lastname as name
  2  from employee
  3  start with emp_no = 2
  4  connect by prior emp_no = mgr
  5  ORDER BY LEVEL;
NAME
--------------------
Last
  Horry
  Roke
  Wash
  Bush
5 rows selected.
SQL>
SQL> drop table employee;
Table dropped.
SQL>
SQL> --



Traversing Upward Through the Tree

 

SQL> CREATE TABLE employee (
  2    employee_id INTEGER,
  3    manager_id INTEGER,
  4    first_name VARCHAR2(10) NOT NULL,
  5    last_name VARCHAR2(10) NOT NULL,
  6    title VARCHAR2(20),
  7    salary NUMBER(6, 0)
  8  );
Table created.
SQL>
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 1         ,0            , "James"  ,"Smith"  ,"CEO",800000);
1 row created.
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 2         , 1         ,"Ron"     ,"Johnson","Sales Manager",600000);
1 row created.
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 3         , 2         ,"Fred"    ,"Hobbs"  ,"Sales Person",200000);
1 row created.
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 4         , 1         ,"Susan"   ,"Jones"  ,"Support Manager",500000);
1 row created.
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 5         , 2         ,"Rob"     ,"Green"  ,"Sales Person", 40000);
1 row created.
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 6         , 4         ,"Jane"    ,"Brown"  ,"Support Person",45000);
1 row created.
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 7         , 4         ,"John"    ,"Grey"   ,"Support Manager",30000);
1 row created.
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 8         , 7         ,"Jean"    ,"Blue"   ,"Support Person",29000);
1 row created.
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 9         , 6         ,"Henry"   ,"Heyson" ,"Support Person",30000);
1 row created.
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 10        , 1         ,"Kevin"   ,"Black"  ,"Ops Manager",100000);
1 row created.
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 11        , 10        ,"Keith"   ,"Long"   ,"Ops Person",50000);
1 row created.
SQL>
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 12        , 10        ,"Frank"   ,"Howard" ,"Ops Person",45000);
1 row created.
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 13        , 10        ,"Doreen"  ,"Penn"   ,"Ops Person",47000);
1 row created.
SQL>
SQL>
SQL>
SQL>
SQL> select * from employee;
EMPLOYEE_ID MANAGER_ID FIRST_NAME LAST_NAME  TITLE                    SALARY
----------- ---------- ---------- ---------- -------------------- ----------
          1          0 James      Smith      CEO                      800000
          2          1 Ron        Johnson    Sales Manager            600000
          3          2 Fred       Hobbs      Sales Person             200000
          4          1 Susan      Jones      Support Manager          500000
          5          2 Rob        Green      Sales Person              40000
          6          4 Jane       Brown      Support Person            45000
          7          4 John       Grey       Support Manager           30000
          8          7 Jean       Blue       Support Person            29000
          9          6 Henry      Heyson     Support Person            30000
         10          1 Kevin      Black      Ops Manager              100000
         11         10 Keith      Long       Ops Person                50000
         12         10 Frank      Howard     Ops Person                45000
         13         10 Doreen     Penn       Ops Person                47000
13 rows selected.
SQL>
SQL> -- Traversing Upward Through the Tree
SQL>
SQL> SELECT LEVEL,
  2   LPAD(" ", 2 * LEVEL - 1) || first_name || " " ||
  3   last_name AS employee
  4  FROM employee
  5  START WITH last_name = "Blue"
  6  CONNECT BY PRIOR manager_id = employee_id;
     LEVEL EMPLOYEE
---------- -------------------------
         1  Jean Blue
         2    John Grey
         3      Susan Jones
         4        James Smith
SQL>
SQL>
SQL>
SQL>
SQL> drop table employee;
Table dropped.
SQL>
SQL>



Use the COUNT() function and LEVEL to get the number of levels in the tree

 

SQL>
SQL> CREATE TABLE employee (
  2    employee_id INTEGER,
  3    manager_id INTEGER,
  4    first_name VARCHAR2(10) NOT NULL,
  5    last_name VARCHAR2(10) NOT NULL,
  6    title VARCHAR2(20),
  7    salary NUMBER(6, 0)
  8  );
Table created.
SQL>
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 1         ,0            , "James"  ,"Smith"  ,"CEO",800000);
1 row created.
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 2         , 1         ,"Ron"     ,"Johnson","Sales Manager",600000);
1 row created.
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 3         , 2         ,"Fred"    ,"Hobbs"  ,"Sales Person",200000);
1 row created.
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 4         , 1         ,"Susan"   ,"Jones"  ,"Support Manager",500000);
1 row created.
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 5         , 2         ,"Rob"     ,"Green"  ,"Sales Person", 40000);
1 row created.
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 6         , 4         ,"Jane"    ,"Brown"  ,"Support Person",45000);
1 row created.
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 7         , 4         ,"John"    ,"Grey"   ,"Support Manager",30000);
1 row created.
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 8         , 7         ,"Jean"    ,"Blue"   ,"Support Person",29000);
1 row created.
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 9         , 6         ,"Henry"   ,"Heyson" ,"Support Person",30000);
1 row created.
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 10        , 1         ,"Kevin"   ,"Black"  ,"Ops Manager",100000);
1 row created.
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 11        , 10        ,"Keith"   ,"Long"   ,"Ops Person",50000);
1 row created.
SQL>
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 12        , 10        ,"Frank"   ,"Howard" ,"Ops Person",45000);
1 row created.
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 13        , 10        ,"Doreen"  ,"Penn"   ,"Ops Person",47000);
1 row created.
SQL>
SQL>
SQL>
SQL>
SQL> select * from employee;
EMPLOYEE_ID MANAGER_ID FIRST_NAME LAST_NAME  TITLE                    SALARY
----------- ---------- ---------- ---------- -------------------- ----------
          1          0 James      Smith      CEO                      800000
          2          1 Ron        Johnson    Sales Manager            600000
          3          2 Fred       Hobbs      Sales Person             200000
          4          1 Susan      Jones      Support Manager          500000
          5          2 Rob        Green      Sales Person              40000
          6          4 Jane       Brown      Support Person            45000
          7          4 John       Grey       Support Manager           30000
          8          7 Jean       Blue       Support Person            29000
          9          6 Henry      Heyson     Support Person            30000
         10          1 Kevin      Black      Ops Manager              100000
         11         10 Keith      Long       Ops Person                50000
         12         10 Frank      Howard     Ops Person                45000
         13         10 Doreen     Penn       Ops Person                47000
13 rows selected.
SQL>
SQL> --Use the COUNT() function and LEVEL to get the number of levels in the tree
SQL>
SQL> SELECT COUNT(DISTINCT LEVEL)
  2  FROM employee
  3  START WITH employee_id = 1
  4  CONNECT BY PRIOR employee_id = manager_id;
COUNT(DISTINCTLEVEL)
--------------------
                   4
SQL>
SQL>
SQL>
SQL> drop table employee;
Table dropped.
SQL>
SQL>



Using the LEVEL Pseudo-Column:display the level in the tree

 
SQL>
SQL> CREATE TABLE employee (
  2    employee_id INTEGER,
  3    manager_id INTEGER,
  4    first_name VARCHAR2(10) NOT NULL,
  5    last_name VARCHAR2(10) NOT NULL,
  6    title VARCHAR2(20),
  7    salary NUMBER(6, 0)
  8  );
Table created.
SQL>
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 1         ,0            , "James"  ,"Smith"  ,"CEO",800000);
1 row created.
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 2         , 1         ,"Ron"     ,"Johnson","Sales Manager",600000);
1 row created.
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 3         , 2         ,"Fred"    ,"Hobbs"  ,"Sales Person",200000);
1 row created.
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 4         , 1         ,"Susan"   ,"Jones"  ,"Support Manager",500000);
1 row created.
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 5         , 2         ,"Rob"     ,"Green"  ,"Sales Person", 40000);
1 row created.
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 6         , 4         ,"Jane"    ,"Brown"  ,"Support Person",45000);
1 row created.
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 7         , 4         ,"John"    ,"Grey"   ,"Support Manager",30000);
1 row created.
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 8         , 7         ,"Jean"    ,"Blue"   ,"Support Person",29000);
1 row created.
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 9         , 6         ,"Henry"   ,"Heyson" ,"Support Person",30000);
1 row created.
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 10        , 1         ,"Kevin"   ,"Black"  ,"Ops Manager",100000);
1 row created.
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 11        , 10        ,"Keith"   ,"Long"   ,"Ops Person",50000);
1 row created.
SQL>
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 12        , 10        ,"Frank"   ,"Howard" ,"Ops Person",45000);
1 row created.
SQL>
SQL> insert into employee (EMPLOYEE_ID, MANAGER_ID,FIRST_NAME,LAST_NAME,TITLE,SALARY)
  2                 values( 13        , 10        ,"Doreen"  ,"Penn"   ,"Ops Person",47000);
1 row created.
SQL>
SQL>
SQL>
SQL>
SQL> select * from employee;
EMPLOYEE_ID MANAGER_ID FIRST_NAME LAST_NAME  TITLE                    SALARY
----------- ---------- ---------- ---------- -------------------- ----------
          1          0 James      Smith      CEO                      800000
          2          1 Ron        Johnson    Sales Manager            600000
          3          2 Fred       Hobbs      Sales Person             200000
          4          1 Susan      Jones      Support Manager          500000
          5          2 Rob        Green      Sales Person              40000
          6          4 Jane       Brown      Support Person            45000
          7          4 John       Grey       Support Manager           30000
          8          7 Jean       Blue       Support Person            29000
          9          6 Henry      Heyson     Support Person            30000
         10          1 Kevin      Black      Ops Manager              100000
         11         10 Keith      Long       Ops Person                50000
         12         10 Frank      Howard     Ops Person                45000
         13         10 Doreen     Penn       Ops Person                47000
13 rows selected.
SQL>
SQL>
SQL> --Using the LEVEL Pseudo-Column:display the level in the tree
SQL>
SQL> SELECT LEVEL, employee_id, manager_id, first_name, last_name
  2  FROM employee
  3  START WITH employee_id = 1
  4  CONNECT BY PRIOR employee_id = manager_id
  5  ORDER BY LEVEL;
     LEVEL EMPLOYEE_ID MANAGER_ID FIRST_NAME LAST_NAME
---------- ----------- ---------- ---------- ----------
         1           1          0 James      Smith
         2          10          1 Kevin      Black
         2           2          1 Ron        Johnson
         2           4          1 Susan      Jones
         3          13         10 Doreen     Penn
         3           7          4 John       Grey
         3          11         10 Keith      Long
         3           5          2 Rob        Green
         3           3          2 Fred       Hobbs
         3          12         10 Frank      Howard
         3           6          4 Jane       Brown
         4           8          7 Jean       Blue
         4           9          6 Henry      Heyson
13 rows selected.
SQL>
SQL>
SQL>
SQL> drop table employee;
Table dropped.
SQL>
SQL>