Oracle PL/SQL/Conversion Functions/DECODE — различия между версиями

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Текущая версия на 10:01, 26 мая 2010

Create a report that shows number of customers per state.

   
SQL>
SQL>
SQL> create table customer(
  2           cust_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          ,company_name                      varchar2(50)
 14  );
Table created.
SQL>
SQL> insert into customer(cust_no,lastname,firstname,midinit,street,city,state,zip,zip_4,area_code,phone,company_name)
  2                values(1, "Allen", "Joe","J","10 Ave","London","CA","11111","1111","111", "111-1111","Big Company");
1 row created.
SQL> insert into customer(cust_no,lastname,firstname,midinit,street,city,state,zip,zip_4,area_code,phone,company_name)
  2                values(2,"Ward","Sue","W","20 Ave","New York","NY","44444","4444","444", "436-4444","B Company");
1 row created.
SQL> insert into customer(cust_no,lastname,firstname,midinit,street,city,state,zip,zip_4,area_code,phone,company_name)
  2                values(3,"Jason","Pure","J","50 St","Longli","CA","55555","5555","555", "234-4444","C Company");
1 row created.
SQL> insert into customer(cust_no,lastname,firstname,midinit,street,city,state,zip,zip_4,area_code,phone,company_name)
  2                values(4,"Bird","Jill", null,"30 St","Pais","NY","22222","2222","222", "634-7733","D Company");
1 row created.
SQL> insert into customer(cust_no,lastname,firstname,midinit,street,city,state,zip,zip_4,area_code,phone,company_name)
  2                values(5,"Hill","Carl","H","19 Drive","A Town","CA","66666","6566","666", "243-4243","E Company");
1 row created.
SQL> insert into customer(cust_no,lastname,firstname,midinit,street,city,state,zip,zip_4,area_code,phone,company_name)
  2                values(6,"Peter","Yari","P","38 Ave","Small City","NY","77777","7777","777", "454-5443","F Inc");
1 row created.
SQL> insert into customer(cust_no,lastname,firstname,midinit,street,city,state,zip,zip_4,area_code,phone,company_name)
  2                values(7,"Joe","Paula","J","78 St. Apt 3A","Queen City","NY","32322","2323","888", "664-4333","E Inc");
1 row created.
SQL> insert into customer(cust_no,lastname,firstname,midinit,street,city,state,zip,zip_4,area_code,phone,company_name)
  2                values(8,"Chili","Steve","C","38 Ave Apt 62","Mili","CA","88888","8888","787", "456-4566","G Inc");
1 row created.
SQL> insert into customer(cust_no,lastname,firstname,midinit,street,city,state,zip,zip_4,area_code,phone,company_name)
  2                values(9,"Mona","Joe","M","930 Ave933","Kansas City","MO","12345","1234","412", "456-4563","H Inc");
1 row created.
SQL> insert into customer(cust_no,lastname,firstname,midinit,street,city,state,zip,zip_4,area_code,phone,company_name)
  2                values(10,"Hack","Kisi","H","Kings Rd","Bellmore","NY","54321","3898","516", "767-5677","I Inc");
1 row created.
SQL> insert into customer(cust_no,lastname,firstname,midinit,street,city,state,zip,zip_4,area_code,phone,company_name)
  2                values(11,"Bill","Jose","B","12 Giant Rd.","Newton","NJ","23454","1234","958", "123-7367","J Associates");
1 row created.
SQL> insert into customer(cust_no,lastname,firstname,midinit,street,city,state,zip,zip_4,area_code,phone,company_name)
  2                values(12,"Taker","Lawrence","T","1 Sask Rd.","Camp","NJ","19191","3298","928", "123-7384","K Company");
1 row created.
SQL> insert into customer(cust_no,lastname,firstname,midinit,street,city,state,zip,zip_4,area_code,phone,company_name)
  2                values(13,"Richer","Doris","R","213 Easy Street","WarPease","RI","34343","2112","501", "123-7384","L Inc");
1 row created.
SQL> insert into customer( cust_no,lastname,firstname,midinit,street,city,state,zip,zip_4,area_code,phone,company_name)
  2                values(14,"Pete","Doris","P","9 Ave","New York","NY","45454","4222","112", "123-1234","M Company");
1 row created.
SQL>
SQL> select state from customer;
ST
--
CA
NY
CA
NY
CA
NY
NY
CA
MO
NY
NJ
NJ
RI
NY
14 rows selected.
SQL>
SQL> SELECT
  2   SUM ( decode ( state, "NJ" , 1) ) as nj,
  3   SUM ( decode ( state, "NY" , 1) ) as ny,
  4   SUM ( decode ( state, "RI" , 1) ) as ri
  5  FROM customer;
        NJ         NY         RI
---------- ---------- ----------
         2          6          1
1 row selected.
SQL>
SQL>
SQL> drop table customer;
Table dropped.
SQL> --



Decode a column with substr and instr

   
SQL>
SQL> CREATE TABLE old_item (
  2       item_id   CHAR(20),
  3       item_desc CHAR(25)
  4       );
Table created.
SQL>
SQL> INSERT INTO old_item VALUES("LA-101", "Can, Small");
1 row created.
SQL> INSERT INTO old_item VALUES("LA-102", "Can, Large");
1 row created.
SQL> INSERT INTO old_item VALUES("LA-103", "Bottle, Small");
1 row created.
SQL> INSERT INTO old_item VALUES("LA-104", "Bottle, Large");
1 row created.
SQL> INSERT INTO old_item VALUES("NY-101", "Box, Small");
1 row created.
SQL> INSERT INTO old_item VALUES("NY-102", "Box, Large");
1 row created.
SQL> INSERT INTO old_item VALUES("NY-103", "Shipping Carton, Small");
1 row created.
SQL> INSERT INTO old_item VALUES("NY-104", "Shipping Carton, Large");
1 row created.
SQL>
SQL> SELECT item_desc,
  2         SUBSTR(item_desc,
  3                INSTR(item_desc,
  4                      ",",
  5                      1
  6                      ) +2,
  7                99
  8                )
  9  FROM   old_item;
ITEM_DESC                 SUBSTR(ITEM_DESC,INSTR(IT
------------------------- -------------------------
Can, Small                Small
Can, Large                Large
Bottle, Small             Small
Bottle, Large             Large
Box, Small                Small
Box, Large                Large
Shipping Carton, Small    Small
Shipping Carton, Large    Large
8 rows selected.
SQL>
SQL> drop table OLD_ITEM;
Table dropped.
SQL>



DECODE and GROUPING

   
SQL>
SQL> create table ord(
  2           order_no               integer          primary key
  3          ,cust_no                integer
  4          ,order_date             date not null
  5          ,total_order_price      number(7,2)
  6          ,deliver_date           date
  7          ,deliver_time           varchar2(7)
  8          ,payment_method         varchar2(2)
  9          ,emp_no                 number(3,0)
 10          ,deliver_name           varchar2(35)
 11          ,gift_message           varchar2(100)
 12  );
Table created.
SQL>
SQL>
SQL> insert into ord(order_no,cust_no,order_date,total_order_price,deliver_date,deliver_time,payment_method,emp_no,deliver_name,gift_message)
  2           values(1,1,"14-Feb-2002", 23.00, "14-Feb-2002", "12 noon", "CA",1, null, "Gift for wife");
1 row created.
SQL> insert into ord(order_no  ,cust_no ,order_date ,total_order_price ,deliver_date ,deliver_time ,payment_method ,emp_no,deliver_name ,gift_message )
  2           values(2,1,"14-Feb-2003", 510.98, "14-feb-2003", "5 pm", "NY",7, "Rose Ted", "Happy Valentines Day to Mother");
1 row created.
SQL> insert into ord(order_no  ,cust_no ,order_date ,total_order_price ,deliver_date ,deliver_time,payment_method ,emp_no,deliver_name ,gift_message )
  2           values(3, 2,"14-Feb-2004", 315.99, "14-feb-2004", "3 pm", "VS",2, "Ani Forest", "Happy Valentines Day to Father");
1 row created.
SQL> insert into ord(order_no  ,cust_no ,order_date ,total_order_price ,deliver_date ,deliver_time,payment_method ,emp_no,deliver_name ,gift_message )
  2           values(4, 2,"14-Feb-1999", 191.95, "14-feb-1999", "2 pm", "NJ",2, "O. John", "Happy Valentines Day");
1 row created.
SQL> insert into ord(order_no  ,cust_no ,order_date ,total_order_price ,deliver_date ,deliver_time,payment_method ,emp_no,deliver_name ,gift_message    )
  2           values(5, 6,"4-mar-2002", 101.95, "5-mar-2002", "2:30 pm", "MO"   , 2, "Cora", "Happy Birthday from John");
1 row created.
SQL> insert into ord(order_no  ,cust_no ,order_date ,total_order_price ,deliver_date ,deliver_time,payment_method ,emp_no,deliver_name ,gift_message )
  2           values(6, 9,"7-apr-2003", 221.95, "7-apr-2003", "3 pm", "MA", 2, "Sake Keith", "Happy Birthday from Joe" );
1 row created.
SQL> insert into ord(order_no  ,cust_no ,order_date ,total_order_price ,deliver_date ,deliver_time,payment_method ,emp_no,deliver_name ,gift_message )
  2           values(7, 9,"20-jun-2004", 315.95, "21-jun-2004", "12 noon", "BC", 2, "Jessica Li", "Happy Birthday from Jessica");
1 row created.
SQL> insert into ord(order_no  ,cust_no ,order_date ,total_order_price ,deliver_date ,deliver_time,payment_method ,emp_no,deliver_name ,gift_message )
  2           values (8, 12, "31-dec-1999", 135.95, "1-jan-2000", "12 noon", "DI",      3, "Larry", "Happy New Year from Lawrence");
1 row created.
SQL> insert into ord(order_no  ,cust_no ,order_date ,total_order_price ,deliver_date ,deliver_time,payment_method ,emp_no,deliver_name ,gift_message )
  2           values (9, 12, "26-dec-2003", 715.95, "2-jan-2004", "12 noon", "SK",7, "Did", "Happy Birthday from Nancy" );
1 row created.
SQL> insert into ord(order_no  ,cust_no ,order_date ,total_order_price ,deliver_date ,deliver_time,payment_method ,emp_no,deliver_name ,gift_message )
  2           values(10, 4, sysdate-1, 119.95, sysdate+2, "6:30 pm", "VG",2, "P. Jing", "Happy Valentines Day to Jason");
1 row created.
SQL> insert into ord(order_no  ,cust_no ,order_date ,total_order_price ,deliver_date ,deliver_time,payment_method ,emp_no,deliver_name ,gift_message )
  2           values(11, 2, sysdate, 310.00, sysdate+2, "3:30 pm", "DC",2, "C. Late", "Happy Birthday Day to Jack");
1 row created.
SQL> insert into ord(order_no  ,cust_no ,order_date ,total_order_price ,deliver_date ,deliver_time,payment_method ,emp_no,deliver_name ,gift_message)
  2           values(12, 7, sysdate-3, 121.95, sysdate-2, "1:30 pm", "AC",2, "W. Last", "Happy Birthday Day to You");
1 row created.
SQL> insert into ord(order_no  ,cust_no ,order_date ,total_order_price ,deliver_date ,deliver_time,payment_method ,emp_no,deliver_name ,gift_message)
  2           values(13, 7, sysdate, 211.95, sysdate-4, "4:30 pm", "CA",2, "J. Bond", "Thanks for hard working");
1 row created.
SQL>
SQL>
SQL> select * from ord;
  ORDER_NO    CUST_NO ORDER_DATE           TOTAL_ORDER_PRICE DELIVER_DATE         DELIVER PA     EMP_NO DELIVER_NAME
---------- ---------- -------------------- ----------------- -------------------- ------- -- ---------- -----------------------------------
GIFT_MESSAGE
----------------------------------------------------------------------------------------------------
         1          1 14-FEB-2002 00:00:00                23 14-FEB-2002 00:00:00 12 noon CA          1
Gift for wife
         2          1 14-FEB-2003 00:00:00            510.98 14-FEB-2003 00:00:00 5 pm    NY          7 Rose Ted
Happy Valentines Day to Mother
         3          2 14-FEB-2004 00:00:00            315.99 14-FEB-2004 00:00:00 3 pm    VS          2 Ani Forest
Happy Valentines Day to Father
         4          2 14-FEB-1999 00:00:00            191.95 14-FEB-1999 00:00:00 2 pm    NJ          2 O. John
Happy Valentines Day
         5          6 04-MAR-2002 00:00:00            101.95 05-MAR-2002 00:00:00 2:30 pm MO          2 Cora
Happy Birthday from John
         6          9 07-APR-2003 00:00:00            221.95 07-APR-2003 00:00:00 3 pm    MA          2 Sake Keith
Happy Birthday from Joe
         7          9 20-JUN-2004 00:00:00            315.95 21-JUN-2004 00:00:00 12 noon BC          2 Jessica Li
Happy Birthday from Jessica
         8         12 31-DEC-1999 00:00:00            135.95 01-JAN-2000 00:00:00 12 noon DI          3 Larry
Happy New Year from Lawrence
         9         12 26-DEC-2003 00:00:00            715.95 02-JAN-2004 00:00:00 12 noon SK          7 Did
Happy Birthday from Nancy
        10          4 15-JUN-2008 17:42:32            119.95 18-JUN-2008 17:42:32 6:30 pm VG          2 P. Jing
Happy Valentines Day to Jason
        11          2 16-JUN-2008 17:42:33               310 18-JUN-2008 17:42:33 3:30 pm DC          2 C. Late
Happy Birthday Day to Jack
        12          7 13-JUN-2008 17:42:34            121.95 14-JUN-2008 17:42:34 1:30 pm AC          2 W. Last
Happy Birthday Day to You
        13          7 16-JUN-2008 17:42:35            211.95 12-JUN-2008 17:42:35 4:30 pm CA          2 J. Bond
Thanks for hard working

13 rows selected.
SQL>
SQL> SELECT DECODE(GROUPING(cust_no), 1,"All Custs", cust_no) AS cust_no,
  2         DECODE(GROUPING(payment_method), 1, "All PMs", payment_method) AS pay_meth,
  3         to_char(sum(total_order_price), "999.99") AS sales
  4  FROM ord
  5  WHERE cust_no IN (2,12)
  6  GROUP BY CUBE (cust_no, payment_method)
  7  ORDER BY 1,3
  8  /
CUST_NO                                  PAY_MET SALES
---------------------------------------- ------- -------
12                                       DI       135.95
12                                       SK       715.95
12                                       All PMs  851.90
2                                        NJ       191.95
2                                        DC       310.00
2                                        VS       315.99
2                                        All PMs  817.94
All Custs                                DI       135.95
All Custs                                NJ       191.95
All Custs                                DC       310.00
All Custs                                VS       315.99
All Custs                                SK       715.95
All Custs                                All PMs #######
13 rows selected.
SQL>
SQL>
SQL> drop table ord;
Table dropped.
SQL>
SQL> --



DECODE and substr function

   
SQL>
SQL>
SQL> CREATE TABLE old_item (
  2       item_id   CHAR(20),
  3       item_desc CHAR(25)
  4       );
Table created.
SQL>
SQL> INSERT INTO old_item VALUES("LA-101", "Can, Small");
1 row created.
SQL> INSERT INTO old_item VALUES("LA-102", "Can, Large");
1 row created.
SQL> INSERT INTO old_item VALUES("LA-103", "Bottle, Small");
1 row created.
SQL> INSERT INTO old_item VALUES("LA-104", "Bottle, Large");
1 row created.
SQL> INSERT INTO old_item VALUES("NY-101", "Box, Small");
1 row created.
SQL> INSERT INTO old_item VALUES("NY-102", "Box, Large");
1 row created.
SQL> INSERT INTO old_item VALUES("NY-103", "Shipping Carton, Small");
1 row created.
SQL> INSERT INTO old_item VALUES("NY-104", "Shipping Carton, Large");
1 row created.
SQL>
SQL>
SQL> SELECT DECODE(SUBSTR(item_id, 1, 2),
  2                "LA", "Western",
  3                "NY", "Eastern",
  4                "* Unknown *"
  5                ) "Region",
  6         SUBSTR(item_id, 4,3) "Item ID",
  7         item_desc
  8  FROM   old_item;
Region      Ite ITEM_DESC
----------- --- -------------------------
Western     101 Can, Small
Western     102 Can, Large
Western     103 Bottle, Small
Western     104 Bottle, Large
Eastern     101 Box, Small
Eastern     102 Box, Large
Eastern     103 Shipping Carton, Small
Eastern     104 Shipping Carton, Large
8 rows selected.
SQL>
SQL> drop table OLD_ITEM;
Table dropped.
SQL>
SQL>
SQL>



Decode char value to number

   
SQL>
SQL> CREATE TABLE myStudent (
  2    student_id NUMBER(5) NOT NULL,
  3    department CHAR(3)   NOT NULL,
  4    course     NUMBER(3) NOT NULL,
  5    grade      CHAR(1)
  6    );
Table created.
SQL>
SQL> INSERT INTO myStudent (student_id, department, course, grade)
  2                           VALUES (10000, "CS", 102, "A");
1 row created.
SQL>
SQL> INSERT INTO myStudent (student_id, department, course, grade)
  2                           VALUES (10002, "CS", 102, "B");
1 row created.
SQL>
SQL> INSERT INTO myStudent (student_id, department, course, grade)
  2                           VALUES (10003, "CS", 102, "C");
1 row created.
SQL>
SQL> INSERT INTO myStudent (student_id, department, course, grade)
  2                           VALUES (10000, "HIS", 101, "A");
1 row created.
SQL>
SQL> INSERT INTO myStudent (student_id, department, course, grade)
  2                           VALUES (10001, "HIS", 101, "B");
1 row created.
SQL>
SQL> INSERT INTO myStudent (student_id, department, course, grade)
  2                           VALUES (10002, "HIS", 101, "B");
1 row created.
SQL>
SQL> CREATE OR REPLACE FUNCTION AverageGrade (
  2    p_Department IN VARCHAR2,
  3    p_Course IN NUMBER) RETURN VARCHAR2 AS
  4
  5    v_AverageGrade VARCHAR2(1);
  6    v_NumericGrade NUMBER;
  7    v_NumberStudents NUMBER;
  8
  9    CURSOR c_Grades IS
 10      SELECT grade
 11        FROM myStudent
 12        WHERE department = p_Department
 13        AND course = p_Course;
 14  BEGIN
 15    Debug.Reset;
 16    Debug.Debug("p_Department", p_Department);
 17    Debug.Debug("p_Course", p_Course);
 18
 19    SELECT COUNT(*)
 20      INTO v_NumberStudents
 21      FROM myStudent
 22      WHERE department = p_Department
 23      AND course = p_Course;
 24
 25    Debug.Debug("After select, v_NumberStudents", v_NumberStudents);
 26
 27    IF v_NumberStudents = 0 THEN
 28      RAISE_APPLICATION_ERROR(-20001, "No students registered for " ||
 29        p_Department || " " || p_Course);
 30    END IF;
 31
 32    SELECT AVG(DECODE(grade, "A", 5,
 33                             "B", 4,
 34                             "C", 3,
 35                             "D", 2,
 36                             "E", 1))
 37      INTO v_NumericGrade
 38      FROM myStudent
 39      WHERE department = p_Department
 40        AND course = p_Course;
 41
 42    SELECT DECODE(ROUND(v_NumericGrade), 5, "A",
 43                                         4, "B",
 44                                         3, "C",
 45                                         2, "D",
 46                                         1, "E")
 47      INTO v_AverageGrade
 48      FROM dual;
 49
 50    RETURN v_AverageGrade;
 51  END AverageGrade;
 52  /
Function created.
SQL>
SQL>
SQL>
SQL>
SQL>
SQL> drop table myStudent;
Table dropped.



decode column data to output more meaningful information

    
SQL> create table gift(
  2           gift_id                integer         primary key
  3          ,emp_id                integer
  4          ,register_date              date not null
  5          ,total_price        number(7,2)
  6          ,deliver_date           date
  7          ,deliver_time           varchar2(7)
  8          ,payment        varchar2(2)
  9          ,emp_no                 number(3,0)
 10          ,deliver_name           varchar2(35)
 11          ,message        varchar2(100)
 12  );
Table created.
SQL>
SQL> insert into gift(gift_id,emp_id,register_date,total_price,deliver_date,deliver_time,payment,emp_no,deliver_name,message)values
  2                 (1,1,"14-Feb-1999", 123.12, "14-Feb-1999", "12 noon", "CA",1, null, "Happy Birthday to you");
1 row created.
SQL> insert into gift(gift_id  ,emp_id ,register_date ,total_price ,deliver_date ,deliver_time ,payment ,emp_no,deliver_name ,message)values
  2                 (2,1,"14-Feb-1999", 50.98, "14-feb-1999", "1 pm", "CA",7, "name1", "Happy Birthday");
1 row created.
SQL> insert into gift(gift_id  ,emp_id ,register_date ,total_price ,deliver_date ,deliver_time,payment ,emp_no,deliver_name ,message )values
  2                 (3, 2,"14-Feb-1999", 35.99, "14-feb-1999", "1 pm", "VS",2, "Tom", "Happy Birthday");
1 row created.
SQL> insert into gift(gift_id  ,emp_id ,register_date ,total_price ,deliver_date ,deliver_time,payment ,emp_no,deliver_name ,message )values
  2                 (4, 2,"14-Feb-1999", 19.95, "14-feb-1999", "5 pm", "CA",2, "Mary", "Happy Birthday");
1 row created.
SQL> insert into gift(gift_id  ,emp_id ,register_date ,total_price ,deliver_date ,deliver_time,payment ,emp_no,deliver_name ,message)values
  2                 (5, 6,"4-mar-1999", 10.95, "5-mar-1999", "4:30 pm", "VS", 2, "Jack", "Happy Birthday");
1 row created.
SQL>
SQL>
SQL>
SQL> select gift_id, decode(payment,
  2  "VS", "VISA Card Standard",
  3  "VG", "VISA Gold Card",
  4  "AX", "American Express",
  5  "MC", "Master Card",
  6  "DI", "Discover Card",
  7  "CA", "Cash",
  8  "CK", "Check",
  9  "Unknown")
 10    from gift ;
   GIFT_ID DECODE(PAYMENT,"VS
---------- ------------------
         1 Cash
         2 Cash
         3 VISA Card Standard
         4 Cash
         5 VISA Card Standard
5 rows selected.
SQL>
SQL>
SQL> drop table gift;
Table dropped.



Decode for more than one key value pair

   
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 dept;
    DEPTNO DNAME          LOC
---------- -------------- -------------
        10 ACCOUNTING     NEW YORK
        20 RESEARCH       DALLAS
        30 SALES          CHICAGO
        40 OPERATIONS     BOSTON
4 rows selected.
SQL>
SQL> select dname, decode( loc, "BOSTON", "Red Sox fans",
  2                             "CHICAGO", "White Sox fans",
  3                             "DALLAS", "Astros fans",
  4                             "NEW YORK", "Mets fans" ) "Baseball Team"
  5  from dept;
DNAME          Baseball Team
-------------- --------------
ACCOUNTING     Mets fans
RESEARCH       Astros fans
SALES          White Sox fans
OPERATIONS     Red Sox fans
4 rows selected.
SQL>
SQL> drop table dept;
Table dropped.
SQL> --



DECODE in the GROUP BY clause

   
SQL>
SQL> create table emp(
  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          ,shortZipCode           varchar2(4)
 11          ,area_code              varchar2(3)
 12          ,phone                  varchar2(8)
 13          ,salary                 number(5,2)
 14          ,birthdate              date
 15          ,startDate              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>
SQL> -- emp Table Inserts:
SQL> insert into emp(emp_no, lastname, firstname, midinit, street, city, state, zip,shortZipCode, area_code, phone, birthdate, title)values
  2                      (1,"Z","Joy","R","1 Ave","New York","NY","12122","2333","212","200-1111","12-nov-1976","President");
1 row created.
SQL>
SQL>
SQL> create or replace view avg_Sal
  2  as select trunc(avg(salary)) avg_sal
  3  from emp
  4  /
View created.
SQL>
SQL>
SQL> select
  2  decode(  sign( (salary - avg_sal ) ),
  3       1, "> Average of " || to_char(avg_sal, "99.99") ,
  4       0, "= Average of " || to_char(avg_sal, "99.99"),
  5          -1, "< Average of " || to_char(avg_sal, "99.99")  ) sal_desc,
  6   count(*)
  7  from emp, avg_sal
  8  group by
  9  decode(  sign( (salary - avg_sal ) ),
 10       1, "> Average of " || to_char(avg_sal, "99.99") ,
 11       0, "= Average of " || to_char(avg_sal, "99.99"),
 12          -1, "< Average of " || to_char(avg_sal, "99.99")  )
 13  /
                             1
1 row selected.
SQL>
SQL> drop table emp;
Table dropped.



Decode statement could be easily rewritten using the CASE statement

   
SQL>
SQL> CREATE TABLE myCar
  2  (
  3    MAKER  VARCHAR (25),
  4    MODEL  VARCHAR (25),
  5    PRICE  NUMERIC
  6  );
Table created.
SQL>
SQL> INSERT INTO myCar VALUES("CHRYSLER","CROSSFIRE",33620);
1 row created.
SQL> INSERT INTO myCar VALUES("CHRYSLER","300M",29185);
1 row created.
SQL> INSERT INTO myCar VALUES("HONDA","CIVIC",15610);
1 row created.
SQL> INSERT INTO myCar VALUES("HONDA","ACCORD",19300);
1 row created.
SQL>
SQL> INSERT INTO myCar VALUES("FORD","MUSTANG",15610);
1 row created.
SQL> INSERT INTO myCar VALUES("FORD","LATESTnGREATEST",NULL);
1 row created.
SQL> INSERT INTO myCar VALUES("FORD","FOCUS",13005);
1 row created.
SQL>
SQL> SELECT
  2     model,
  3     DECODE(maker, "CHRYSLER","DOMESTIC"
  4           ,"FORD","DOMESTIC"
  5           ,"FOREIGN")
  6  FROM myCar;
MODEL                     DECODE(M
------------------------- --------
CROSSFIRE                 DOMESTIC
300M                      DOMESTIC
CIVIC                     FOREIGN
ACCORD                    FOREIGN
MUSTANG                   DOMESTIC
LATESTnGREATEST           DOMESTIC
FOCUS                     DOMESTIC
7 rows selected.
SQL>
SQL> SELECT
  2        model,
  3        CASE maker
  4        WHEN "CHRYSLER"      THEN "DOMESTIC"
  5        WHEN "FORD"          THEN "DOMESTIC"
  6        ELSE                "FOREIGN"
  7        END
  8   FROM myCar;
MODEL                     CASEMAKE
------------------------- --------
CROSSFIRE                 DOMESTIC
300M                      DOMESTIC
CIVIC                     FOREIGN
ACCORD                    FOREIGN
MUSTANG                   DOMESTIC
LATESTnGREATEST           DOMESTIC
FOCUS                     DOMESTIC
7 rows selected.
SQL>
SQL> drop table myCar;
Table dropped.



Decode the result from row_number over, partition by, order by

   
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> select * from emp;
   EMPNO ENAME      JOB            MGR HIREDATE       SAL     COMM DEPTNO
-------- ---------- --------- -------- --------- -------- -------- ------
 7369.00 SMITH      CLERK      7902.00 17-DEC-80   800.00              20
 7499.00 ALLEN      SALESMAN   7698.00 20-FEB-81  1600.00   300.00     30
 7521.00 WARD       SALESMAN   7698.00 22-FEB-81  1250.00   500.00
 7566.00 JONES      MANAGER    7839.00 02-APR-81  2975.00              20
 7654.00 MARTIN     SALESMAN   7698.00 28-SEP-81  1250.00  1400.00     30
 7698.00 BLAKE      MANAGER    7839.00 01-MAY-81  2850.00
 7782.00 CLARK      MANAGER    7839.00 09-JUN-81  2450.00              10
   EMPNO ENAME      JOB            MGR HIREDATE       SAL     COMM DEPTNO
-------- ---------- --------- -------- --------- -------- -------- ------
 7788.00 SCOTT      ANALYST    7566.00 09-DEC-82  3000.00              20
 7839.00 KING       PRESIDENT          17-NOV-81  5000.00              10
 7844.00 TURNER     SALESMAN   7698.00 08-SEP-81  1500.00      .00     30
 7876.00 ADAMS      CLERK      7788.00 12-JAN-83  1100.00              20
 7900.00 JAMES      CLERK      7698.00 03-DEC-81   950.00              30

   EMPNO ENAME      JOB            MGR HIREDATE       SAL     COMM DEPTNO
-------- ---------- --------- -------- --------- -------- -------- ------
 7902.00 FORD       ANALYST    7566.00 03-DEC-81  3000.00              20
 7934.00 MILLER     CLERK      7782.00 23-JAN-82  1300.00              10

14 rows selected.
SQL>
SQL>
SQL> set echo on
SQL>
SQL> select deptno,
  2             max(decode(seq,1,ename,null)) highest_paid,
  3             max(decode(seq,2,ename,null)) second_highest,
  4             max(decode(seq,3,ename,null)) third_highest
  5    from ( SELECT deptno, ename,
  6                  row_number() OVER
  7                     (PARTITION BY deptno
  8                          ORDER BY sal desc NULLS LAST ) seq
  9             FROM emp )
 10  where seq <= 3
 11  group by deptno
 12  /
DEPTNO HIGHEST_PA SECOND_HIG THIRD_HIGH
------ ---------- ---------- ----------
    10 KING       CLARK      MILLER
    20 SCOTT      FORD       JONES
    30 BLAKE      ALLEN      TURNER

SQL>
SQL>
SQL> drop table emp;
Table dropped.
SQL>
SQL>
SQL>



Demo range comparison with DECODE

   
SQL>
SQL> create table emp(
  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          ,shortZipCode           varchar2(4)
 11          ,area_code              varchar2(3)
 12          ,phone                  varchar2(8)
 13          ,salary                 number(5,2)
 14          ,birthdate              date
 15          ,startDate              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>
SQL> -- emp Table Inserts:
SQL> insert into emp(emp_no, lastname, firstname, midinit, street, city, state, zip,shortZipCode, area_code, phone, birthdate, title)values
  2                      (1,"Z","Joy","R","1 Ave","New York","NY","12122","2333","212","200-1111","12-nov-1976","President");
1 row created.
SQL>
SQL> create or replace view avg_Sal
  2  as select trunc(avg(salary)) avg_sal
  3  from emp
  4  /
View created.
SQL>
SQL> select lastname, salary,
  2  decode(  sign( salary - avg_sal ),
  3       1, "> Average of " || to_char(avg_sal, "99.99") ,
  4       0, "= Average of " || to_char(avg_sal, "99.99"),
  5          -1, "< Average of " || to_char(avg_sal, "99.99")  ) sal_desc
  6  from emp, avg_sal
  7  /
Z
1 row selected.
SQL>
SQL> drop table emp;
Table dropped.



Extract any procedure, function or package

   
SQL> --
SQL>
SQL>
SQL>
SQL> select decode( type||"-"||to_char(line,"fm99999"),
  2                 "PACKAGE BODY-1", "/"||chr(10),
  3                  null) ||
  4         decode(line,1,"create or replace ", "" ) ||
  5         text text
  6    from user_source
  7   where name = upper("Your PackageName")
  8   order by type, line;
no rows selected
SQL>
SQL>
SQL> --



Format nullable heading

   
SQL>
SQL> column nullable format a10 heading "NULL|ALLOWED?"
SQL>
SQL> SELECT table_name, column_name,
  2         DECODE(nullable, "N", "NO", "YES") nullable
  3  FROM   all_tab_columns
  4  WHERE  table_name = UPPER("&table_name");
Enter value for table_name:
old   4: WHERE  table_name = UPPER("&table_name")
new   4: WHERE  table_name = UPPER("")
no rows selected



Syntax: DECODE

   
SQL>
SQL> CREATE TABLE myCar
  2  (
  3    MAKER  VARCHAR (25),
  4    MODEL  VARCHAR (25),
  5    PRICE  NUMERIC
  6  );
Table created.
SQL>
SQL> INSERT INTO myCar VALUES("CHRYSLER","CROSSFIRE",33620);
1 row created.
SQL> INSERT INTO myCar VALUES("CHRYSLER","300M",29185);
1 row created.
SQL> INSERT INTO myCar VALUES("HONDA","CIVIC",15610);
1 row created.
SQL> INSERT INTO myCar VALUES("HONDA","ACCORD",19300);
1 row created.
SQL>
SQL> INSERT INTO myCar VALUES("FORD","MUSTANG",15610);
1 row created.
SQL> INSERT INTO myCar VALUES("FORD","LATESTnGREATEST",NULL);
1 row created.
SQL> INSERT INTO myCar VALUES("FORD","FOCUS",13005);
1 row created.
SQL>
SQL> SELECT * FROM  myCar;
MAKER                     MODEL                          PRICE
------------------------- ------------------------- ----------
CHRYSLER                  CROSSFIRE                      33620
CHRYSLER                  300M                           29185
HONDA                     CIVIC                          15610
HONDA                     ACCORD                         19300
FORD                      MUSTANG                        15610
FORD                      LATESTnGREATEST
FORD                      FOCUS                          13005
7 rows selected.
SQL>
SQL> SELECT
  2     model,
  3     DECODE(maker, "CHRYSLER","DOMESTIC"
  4           ,"FORD","DOMESTIC"
  5           ,"FOREIGN")
  6  FROM myCar;
MODEL                     DECODE(M
------------------------- --------
CROSSFIRE                 DOMESTIC
300M                      DOMESTIC
CIVIC                     FOREIGN
ACCORD                    FOREIGN
MUSTANG                   DOMESTIC
LATESTnGREATEST           DOMESTIC
FOCUS                     DOMESTIC
7 rows selected.
SQL>
SQL>
SQL> drop table myCar;
Table dropped.



Use DECODE and SIGN functions on the ORD table

   
SQL>
SQL>
SQL>
SQL>
SQL> create table ord(
  2           order_no               integer          primary key
  3          ,cust_no                integer
  4          ,order_date             date not null
  5          ,total_order_price      number(7,2)
  6          ,deliver_date           date
  7          ,deliver_time           varchar2(7)
  8          ,payment_method         varchar2(2)
  9          ,emp_no                 number(3,0)
 10          ,deliver_name           varchar2(35)
 11          ,gift_message           varchar2(100)
 12  );
Table created.
SQL>
SQL>
SQL> insert into ord(order_no,cust_no,order_date,total_order_price,deliver_date,deliver_time,payment_method,emp_no,deliver_name,gift_message)
  2           values(1,1,"14-Feb-2002", 23.00, "14-Feb-2002", "12 noon", "CA",1, null, "Gift for wife");
1 row created.
SQL> insert into ord(order_no  ,cust_no ,order_date ,total_order_price ,deliver_date ,deliver_time ,payment_method ,emp_no,deliver_name ,gift_message )
  2           values(2,1,"14-Feb-2003", 510.98, "14-feb-2003", "5 pm", "NY",7, "Rose Ted", "Happy Valentines Day to Mother");
1 row created.
SQL> insert into ord(order_no  ,cust_no ,order_date ,total_order_price ,deliver_date ,deliver_time,payment_method ,emp_no,deliver_name ,gift_message )
  2           values(3, 2,"14-Feb-2004", 315.99, "14-feb-2004", "3 pm", "VS",2, "Ani Forest", "Happy Valentines Day to Father");
1 row created.
SQL> insert into ord(order_no  ,cust_no ,order_date ,total_order_price ,deliver_date ,deliver_time,payment_method ,emp_no,deliver_name ,gift_message )
  2           values(4, 2,"14-Feb-1999", 191.95, "14-feb-1999", "2 pm", "NJ",2, "O. John", "Happy Valentines Day");
1 row created.
SQL> insert into ord(order_no  ,cust_no ,order_date ,total_order_price ,deliver_date ,deliver_time,payment_method ,emp_no,deliver_name ,gift_message    )
  2           values(5, 6,"4-mar-2002", 101.95, "5-mar-2002", "2:30 pm", "MO"   , 2, "Cora", "Happy Birthday from John");
1 row created.
SQL> insert into ord(order_no  ,cust_no ,order_date ,total_order_price ,deliver_date ,deliver_time,payment_method ,emp_no,deliver_name ,gift_message )
  2           values(6, 9,"7-apr-2003", 221.95, "7-apr-2003", "3 pm", "MA", 2, "Sake Keith", "Happy Birthday from Joe" );
1 row created.
SQL> insert into ord(order_no  ,cust_no ,order_date ,total_order_price ,deliver_date ,deliver_time,payment_method ,emp_no,deliver_name ,gift_message )
  2           values(7, 9,"20-jun-2004", 315.95, "21-jun-2004", "12 noon", "BC", 2, "Jessica Li", "Happy Birthday from Jessica");
1 row created.
SQL> insert into ord(order_no  ,cust_no ,order_date ,total_order_price ,deliver_date ,deliver_time,payment_method ,emp_no,deliver_name ,gift_message )
  2           values (8, 12, "31-dec-1999", 135.95, "1-jan-2000", "12 noon", "DI",      3, "Larry", "Happy New Year from Lawrence");
1 row created.
SQL> insert into ord(order_no  ,cust_no ,order_date ,total_order_price ,deliver_date ,deliver_time,payment_method ,emp_no,deliver_name ,gift_message )
  2           values (9, 12, "26-dec-2003", 715.95, "2-jan-2004", "12 noon", "SK",7, "Did", "Happy Birthday from Nancy" );
1 row created.
SQL> insert into ord(order_no  ,cust_no ,order_date ,total_order_price ,deliver_date ,deliver_time,payment_method ,emp_no,deliver_name ,gift_message )
  2           values(10, 4, sysdate-1, 119.95, sysdate+2, "6:30 pm", "VG",2, "P. Jing", "Happy Valentines Day to Jason");
1 row created.
SQL> insert into ord(order_no  ,cust_no ,order_date ,total_order_price ,deliver_date ,deliver_time,payment_method ,emp_no,deliver_name ,gift_message )
  2           values(11, 2, sysdate, 310.00, sysdate+2, "3:30 pm", "DC",2, "C. Late", "Happy Birthday Day to Jack");
1 row created.
SQL> insert into ord(order_no  ,cust_no ,order_date ,total_order_price ,deliver_date ,deliver_time,payment_method ,emp_no,deliver_name ,gift_message)
  2           values(12, 7, sysdate-3, 121.95, sysdate-2, "1:30 pm", "AC",2, "W. Last", "Happy Birthday Day to You");
1 row created.
SQL> insert into ord(order_no  ,cust_no ,order_date ,total_order_price ,deliver_date ,deliver_time,payment_method ,emp_no,deliver_name ,gift_message)
  2           values(13, 7, sysdate, 211.95, sysdate-4, "4:30 pm", "CA",2, "J. Bond", "Thanks for hard working");
1 row created.
SQL>
SQL>
SQL> select
  2   decode (sign (total_order_price - 30) ,
  3                     -1 , "Small order",
  4                     0  , "Medium Order",
  5                     +1 , "Large Order" )
  6              AS size_order,
  7   count(*)   AS num_orders
  8  from ord
  9   group by
 10    decode (sign (total_order_price - 30) ,
 11                     -1 , "Small order",
 12                     0  , "Medium Order",
 13                     +1 , "Large Order" )
 14  /
SIZE_ORDER   NUM_ORDERS
------------ ----------
Small order           1
Large Order          12
2 rows selected.
SQL>
SQL> drop table ord;
Table dropped.
SQL>
SQL> --



Use decode as if statement and output "high" or "low"

    
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>
SQL>
SQL> select job, ename
  2  ,      decode(greatest(sal,2500)
  3               ,2500,"cheap","expensive") as class
  4  from   emp
  5  where  bdate <date "1964-01-01"
  6  order  by decode(job,"Designer",1,"Designer",2,3);
JOB      ENAME    CLASS
-------- -------- ---------
Designer Black    expensive
Designer Peter    expensive
Tester   Mary     cheap
Manager  Mike     cheap
Coder    Smart    expensive
Coder    Fake     expensive
Tester   Wil      cheap
Tester   Jack     cheap
8 rows selected.
SQL>
SQL>
SQL> drop table emp;
Table dropped.



Use Decode as if statement to logic like "if then else"

   
SQL>
SQL> CREATE TABLE EMP
  2  (EMPNO NUMBER(4) NOT NULL,
  3   ENAME VARCHAR2(10),
  4   JOB VARCHAR2(9),
  5   MGR NUMBER(4),
  6   HIREDATE DATE,
  7   SAL NUMBER(7, 2),
  8   COMM NUMBER(7, 2),
  9   DEPTNO NUMBER(2)
 10  );
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, "KING", "CLERK",     7782,TO_DATE("23-JAN-1982", "DD-MON-YYYY"), 1300, NULL, 10);
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 KING       CLERK           7782 23-JAN-82       1300                    10
14 rows selected.
SQL>
SQL> select decode( ename, "KING", "KING OF THE HILL", ename ) "ENAME"
  2  from emp;
ENAME
----------------
SMITH
ALLEN
WARD
JONES
MARTIN
BLAKE
CLARK
SCOTT
KING OF THE HILL
TURNER
ADAMS
JAMES
FORD
KING OF THE HILL
14 rows selected.
SQL>
SQL> drop table emp;
Table dropped.
SQL> --



Use decode create dynamic select statement

    
SQL> CREATE TABLE EMP(
  2      EMPNO NUMBER(4) NOT NULL,
  3      ENAME VARCHAR2(10),
  4      JOB VARCHAR2(9),
  5      MGR NUMBER(4),
  6      HIREDATE DATE,
  7      SAL NUMBER(7, 2),
  8      COMM NUMBER(7, 2),
  9      DEPTNO NUMBER(2)
 10  );
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 or replace function get_value_static( p_empno in number, p_cname in varchar2 ) return varchar2
  2  as
  3      l_value  varchar2(4000);
  4  begin
  5      select decode( upper(p_cname),
  6                    "ENAME", ename,
  7                    "EMPNO", empno,
  8                    "HIREDATE", to_char(hiredate,"yyyymmddhh24miss"))
  9        into l_value
 10        from emp
 11       where empno = p_empno;
 12
 13      return l_value;
 14  end;
 15  /
Function created.
SQL>
SQL>
SQL>
SQL> drop table emp;
Table dropped.