Using DECODE() and GROUPING() to Convert Multiple Column Values : GROUPING « Analytical Functions « Oracle PL / SQL






Using DECODE() and GROUPING() to Convert Multiple Column Values

 


SQL>
SQL> -- create demo table
SQL> create table Employee(
  2    ID                 VARCHAR2(4 BYTE)         NOT NULL,
  3    First_Name         VARCHAR2(10 BYTE),
  4    Last_Name          VARCHAR2(10 BYTE),
  5    Start_Date         DATE,
  6    End_Date           DATE,
  7    Salary             Number(8,2),
  8    City               VARCHAR2(10 BYTE),
  9    Description        VARCHAR2(15 BYTE)
 10  )
 11  /

Table created.

SQL>
SQL> -- prepare data
SQL> insert into Employee(ID,  First_Name, Last_Name, Start_Date,                     End_Date,                       Salary,  City,       Description)
  2               values ('01','Jason',    'Martin',  to_date('19960725','YYYYMMDD'), to_date('20060725','YYYYMMDD'), 1234.56, 'Toronto',  'Programmer')
  3  /

1 row created.

SQL> insert into Employee(ID,  First_Name, Last_Name, Start_Date,                     End_Date,                       Salary,  City,       Description)
  2                values('02','Alison',   'Mathews', to_date('19760321','YYYYMMDD'), to_date('19860221','YYYYMMDD'), 6661.78, 'Vancouver','Tester')
  3  /

1 row created.

SQL> insert into Employee(ID,  First_Name, Last_Name, Start_Date,                     End_Date,                       Salary,  City,       Description)
  2                values('03','James',    'Smith',   to_date('19781212','YYYYMMDD'), to_date('19900315','YYYYMMDD'), 6544.78, 'Vancouver','Tester')
  3  /

1 row created.

SQL> insert into Employee(ID,  First_Name, Last_Name, Start_Date,                     End_Date,                       Salary,  City,       Description)
  2                values('04','Celia',    'Rice',    to_date('19821024','YYYYMMDD'), to_date('19990421','YYYYMMDD'), 2344.78, 'Vancouver','Manager')
  3  /

1 row created.

SQL> insert into Employee(ID,  First_Name, Last_Name, Start_Date,                     End_Date,                       Salary,  City,       Description)
  2                values('05','Robert',   'Black',   to_date('19840115','YYYYMMDD'), to_date('19980808','YYYYMMDD'), 2334.78, 'Vancouver','Tester')
  3  /

1 row created.

SQL> insert into Employee(ID,  First_Name, Last_Name, Start_Date,                     End_Date,                       Salary, City,        Description)
  2                values('06','Linda',    'Green',   to_date('19870730','YYYYMMDD'), to_date('19960104','YYYYMMDD'), 4322.78,'New York',  'Tester')
  3  /

1 row created.

SQL> insert into Employee(ID,  First_Name, Last_Name, Start_Date,                     End_Date,                       Salary, City,        Description)
  2                values('07','David',    'Larry',   to_date('19901231','YYYYMMDD'), to_date('19980212','YYYYMMDD'), 7897.78,'New York',  'Manager')
  3  /

1 row created.

SQL> insert into Employee(ID,  First_Name, Last_Name, Start_Date,                     End_Date,                       Salary, City,        Description)
  2                values('08','James',    'Cat',     to_date('19960917','YYYYMMDD'), to_date('20020415','YYYYMMDD'), 1232.78,'Vancouver', 'Tester')
  3  /

1 row created.

SQL>
SQL>
SQL>
SQL> -- display data in the table
SQL> select * from Employee
  2  /

ID   FIRST_NAME LAST_NAME  START_DATE  END_DATE        SALARY CITY       DESCRIPTION
---- ---------- ---------- ----------- ----------- ---------- ---------- ---------------
01   Jason      Martin     1996-JUL-25 2006-JUL-25    1234.56 Toronto    Programmer
02   Alison     Mathews    1976-MAR-21 1986-FEB-21    6661.78 Vancouver  Tester
03   James      Smith      1978-DEC-12 1990-MAR-15    6544.78 Vancouver  Tester
04   Celia      Rice       1982-OCT-24 1999-APR-21    2344.78 Vancouver  Manager
05   Robert     Black      1984-JAN-15 1998-AUG-08    2334.78 Vancouver  Tester
06   Linda      Green      1987-JUL-30 1996-JAN-04    4322.78 New York   Tester
07   David      Larry      1990-DEC-31 1998-FEB-12    7897.78 New York   Manager
08   James      Cat        1996-SEP-17 2002-APR-15    1232.78 Vancouver  Tester

8 rows selected.

SQL>
SQL> --Using DECODE() and GROUPING() to Convert Multiple Column Values
SQL>
SQL>
SQL> SELECT DECODE(GROUPING(city), 1, 'All cities', city) AS City,
  2  DECODE(GROUPING(description), 1, 'All Descriptions', description) AS Description,
  3  SUM(salary)
  4  FROM employee
  5  GROUP BY ROLLUP(city, description);

CITY       DESCRIPTION      SUM(SALARY)
---------- ---------------- -----------
Toronto    Programmer           1234.56
Toronto    All Descriptions     1234.56
New York   Tester               4322.78
New York   Manager              7897.78
New York   All Descriptions    12220.56
Vancouver  Tester              16774.12
Vancouver  Manager              2344.78
Vancouver  All Descriptions     19118.9
All cities All Descriptions    32574.02

9 rows selected.

SQL>
SQL>
SQL>
SQL> -- clean the table
SQL> drop table Employee
  2  /

Table dropped.

SQL>
SQL>
           
         
  








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1.GROUPING() returns 0 for the rows that have non-null values, and 1 for the last row that has a null value
2.GROUPING(x): either zero or one
3.Using DECODE() to Convert the Returned Value from GROUPING()
4.Using GROUPING() with CUBE
5.Demonstrate GROUPING in the HAVING clause
6.having grouping(c.class_desc) = 1