Oracle PL/SQL Tutorial/Query Select/HAVING

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Adds an ORDER BY clause

   <source lang="sql">

SQL> SQL> 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_DAT END_DATE SALARY CITY DESCRIPTION


---------- ---------- --------- --------- ---------- ---------- ---------------

01 Jason Martin 25-JUL-96 25-JUL-06 1234.56 Toronto Programmer 02 Alison Mathews 21-MAR-76 21-FEB-86 6661.78 Vancouver Tester 03 James Smith 12-DEC-78 15-MAR-90 6544.78 Vancouver Tester 04 Celia Rice 24-OCT-82 21-APR-99 2344.78 Vancouver Manager 05 Robert Black 15-JAN-84 08-AUG-98 2334.78 Vancouver Tester 06 Linda Green 30-JUL-87 04-JAN-96 4322.78 New York Tester 07 David Larry 31-DEC-90 12-FEB-98 7897.78 New York Manager 08 James Cat 17-SEP-96 15-APR-02 1232.78 Vancouver Tester 8 rows selected. SQL> SQL> SQL> SELECT city, AVG(salary)

 2  FROM employee
 3  WHERE salary < 50000
 4  GROUP BY city
 5  HAVING AVG(salary) > 3000
 6  ORDER BY AVG(salary);

CITY AVG(SALARY)


-----------

Vancouver 3823.78 New York 6110.28 SQL> SQL> SQL> -- clean the table SQL> drop table Employee

 2  /

Table dropped. SQL> SQL></source>


Display department number and its employee count if it has more than 4 employees

   <source lang="sql">

SQL> SQL> create table employees(

 2    empno      NUMBER(4)
 3  , ename      VARCHAR2(8)
 4  , init       VARCHAR2(5)
 5  , job        VARCHAR2(8)
 6  , mgr        NUMBER(4)
 7  , bdate      DATE
 8  , msal       NUMBER(6,2)
 9  , comm       NUMBER(6,2)
10  , deptno     NUMBER(2) ) ;

Table created. SQL> SQL> SQL> insert into employees values(1,"Jason", "N", "TRAINER", 2, date "1965-12-18", 800 , NULL, 10); 1 row created. SQL> insert into employees values(2,"Jerry", "J", "SALESREP",3, date "1966-11-19", 1600, 300, 10); 1 row created. SQL> insert into employees values(3,"Jord", "T" , "SALESREP",4, date "1967-10-21", 1700, 500, 20); 1 row created. SQL> insert into employees values(4,"Mary", "J", "MANAGER", 5, date "1968-09-22", 1800, NULL, 20); 1 row created. SQL> insert into employees values(5,"Joe", "P", "SALESREP",6, date "1969-08-23", 1900, 1400, 30); 1 row created. SQL> insert into employees values(6,"Black", "R", "MANAGER", 7, date "1970-07-24", 2000, NULL, 30); 1 row created. SQL> insert into employees values(7,"Red", "A", "MANAGER", 8, date "1971-06-25", 2100, NULL, 40); 1 row created. SQL> insert into employees values(8,"White", "S", "TRAINER", 9, date "1972-05-26", 2200, NULL, 40); 1 row created. SQL> insert into employees values(9,"Yellow", "C", "DIRECTOR",10, date "1973-04-27", 2300, NULL, 20); 1 row created. SQL> insert into employees values(10,"Pink", "J", "SALESREP",null,date "1974-03-28", 2400, 0, 30); 1 row created. SQL> SQL> SQL> select deptno, count(empno)

 2  from   employees
 3  group  by deptno
 4  having count(*) >= 4;

no rows selected SQL> SQL> SQL> drop table employees; Table dropped. SQL> SQL></source>


In what city do we have the most employees?

   <source lang="sql">

SQL> 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("20060

725","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("19860

221","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("19900

315","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("19990

421","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("19980

808","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("19960

104","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("19980

212","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("20020

415","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_DAT END_DATE SALARY CITY DESCRIPTION


---------- ---------- --------- --------- ---------- ---------- ---------------

01 Jason Martin 25-JUL-96 25-JUL-06 1234.56 Toronto Programmer 02 Alison Mathews 21-MAR-76 21-FEB-86 6661.78 Vancouver Tester 03 James Smith 12-DEC-78 15-MAR-90 6544.78 Vancouver Tester 04 Celia Rice 24-OCT-82 21-APR-99 2344.78 Vancouver Manager 05 Robert Black 15-JAN-84 08-AUG-98 2334.78 Vancouver Tester 06 Linda Green 30-JUL-87 04-JAN-96 4322.78 New York Tester 07 David Larry 31-DEC-90 12-FEB-98 7897.78 New York Manager 08 James Cat 17-SEP-96 15-APR-02 1232.78 Vancouver Tester 8 rows selected. SQL> SQL> SQL> SELECT count(*), city

 2  FROM employee
 3  GROUP BY city
 4  HAVING count(*) =
 5  (SELECT max(count(*))
 6  FROM employee
 7  GROUP BY CITY);
 COUNT(*) CITY

----------
        5 Vancouver

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

 2  /

Table dropped. SQL> SQL> SQL></source>


List department who has more than 4 employee born after 1960

   <source lang="sql">

SQL> SQL> create table employees(

 2    empno      NUMBER(4)
 3  , ename      VARCHAR2(8)
 4  , init       VARCHAR2(5)
 5  , job        VARCHAR2(8)
 6  , mgr        NUMBER(4)
 7  , bdate      DATE
 8  , msal       NUMBER(6,2)
 9  , comm       NUMBER(6,2)
10  , deptno     NUMBER(2) ) ;

Table created. SQL> SQL> SQL> insert into employees values(1,"Jason", "N", "TRAINER", 2, date "1965-12-18", 800 , NULL, 10); 1 row created. SQL> insert into employees values(2,"Jerry", "J", "SALESREP",3, date "1966-11-19", 1600, 300, 10); 1 row created. SQL> insert into employees values(3,"Jord", "T" , "SALESREP",4, date "1967-10-21", 1700, 500, 20); 1 row created. SQL> insert into employees values(4,"Mary", "J", "MANAGER", 5, date "1968-09-22", 1800, NULL, 20); 1 row created. SQL> insert into employees values(5,"Joe", "P", "SALESREP",6, date "1969-08-23", 1900, 1400, 30); 1 row created. SQL> insert into employees values(6,"Black", "R", "MANAGER", 7, date "1970-07-24", 2000, NULL, 30); 1 row created. SQL> insert into employees values(7,"Red", "A", "MANAGER", 8, date "1971-06-25", 2100, NULL, 40); 1 row created. SQL> insert into employees values(8,"White", "S", "TRAINER", 9, date "1972-05-26", 2200, NULL, 40); 1 row created. SQL> insert into employees values(9,"Yellow", "C", "DIRECTOR",10, date "1973-04-27", 2300, NULL, 20); 1 row created. SQL> insert into employees values(10,"Pink", "J", "SALESREP",null,date "1974-03-28", 2400, 0, 30); 1 row created. SQL> SQL> select deptno, count(empno)

 2  from     employees
 3  where    bdate > date "1960-01-01"
 4  group by deptno
 5  having   count(*) >= 4;

no rows selected SQL> SQL> SQL> drop table employees; Table dropped. SQL></source>


List the employees whose salary is higher than the average salary with self join

   <source lang="sql">

SQL> SQL> SQL> create table employees(

 2    empno      NUMBER(4)
 3  , ename      VARCHAR2(8)
 4  , init       VARCHAR2(5)
 5  , job        VARCHAR2(8)
 6  , mgr        NUMBER(4)
 7  , bdate      DATE
 8  , msal       NUMBER(6,2)
 9  , comm       NUMBER(6,2)
10  , deptno     NUMBER(2) ) ;

Table created. SQL> SQL> SQL> insert into employees values(1,"Jason", "N", "TRAINER", 2, date "1965-12-18", 800 , NULL, 10); 1 row created. SQL> insert into employees values(2,"Jerry", "J", "SALESREP",3, date "1966-11-19", 1600, 300, 10); 1 row created. SQL> insert into employees values(3,"Jord", "T" , "SALESREP",4, date "1967-10-21", 1700, 500, 20); 1 row created. SQL> insert into employees values(4,"Mary", "J", "MANAGER", 5, date "1968-09-22", 1800, NULL, 20); 1 row created. SQL> insert into employees values(5,"Joe", "P", "SALESREP",6, date "1969-08-23", 1900, 1400, 30); 1 row created. SQL> insert into employees values(6,"Black", "R", "MANAGER", 7, date "1970-07-24", 2000, NULL, 30); 1 row created. SQL> insert into employees values(7,"Red", "A", "MANAGER", 8, date "1971-06-25", 2100, NULL, 40); 1 row created. SQL> insert into employees values(8,"White", "S", "TRAINER", 9, date "1972-05-26", 2200, NULL, 40); 1 row created. SQL> insert into employees values(9,"Yellow", "C", "DIRECTOR",10, date "1973-04-27", 2300, NULL, 20); 1 row created. SQL> insert into employees values(10,"Pink", "J", "SALESREP",null,date "1974-03-28", 2400, 0, 30); 1 row created. SQL> SQL> select e1.empno

 2  from     employees e1
 3  ,        employees e2
 4  group by e1.empno
 5  ,        e1.msal
 6  having   e1.msal > avg(e2.msal);
    EMPNO

        7
        8
        9
       10
        6
        5

6 rows selected. SQL> SQL> SQL> drop table employees; Table dropped. SQL></source>


Use Having

Say you want to view the cities that have an average salary greater than $50000.

To do this, you

  1. Use the GROUP BY clause to group rows into blocks with the same city.
  2. Use the HAVING clause to limit the returned results to those groups that have an average salary greater than $50000.



   <source lang="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_DAT END_DATE SALARY CITY DESCRIPTION


---------- ---------- --------- --------- ---------- ---------- ---------------

01 Jason Martin 25-JUL-96 25-JUL-06 1234.56 Toronto Programmer 02 Alison Mathews 21-MAR-76 21-FEB-86 6661.78 Vancouver Tester 03 James Smith 12-DEC-78 15-MAR-90 6544.78 Vancouver Tester 04 Celia Rice 24-OCT-82 21-APR-99 2344.78 Vancouver Manager 05 Robert Black 15-JAN-84 08-AUG-98 2334.78 Vancouver Tester 06 Linda Green 30-JUL-87 04-JAN-96 4322.78 New York Tester 07 David Larry 31-DEC-90 12-FEB-98 7897.78 New York Manager 08 James Cat 17-SEP-96 15-APR-02 1232.78 Vancouver Tester 8 rows selected. SQL> SQL> SQL> SELECT city, AVG(salary)

 2  FROM employee
 3  GROUP BY city
 4  HAVING AVG(salary) > 50000;

no rows selected SQL> SQL> SQL> -- clean the table SQL> drop table Employee

 2  /

Table dropped. SQL> SQL></source>


Using the HAVING Clause to Filter Groups of Rows

You use the HAVING clause to filter groups of rows.

GROUP BY can be used without HAVING.

But HAVING must be used in conjunction with GROUP BY.

You place the HAVING clause after your GROUP BY clause:



   <source lang="sql">

SELECT ... FROM ... WHERE GROUP BY ... HAVING ... ORDER BY ...;</source>


Using the WHERE, GROUP BY, and HAVING Clauses Together

The WHERE clause first filters the rows, then the remaining rows are grouped into blocks by the GROUP BY clause, and finally the row groups are filtered by the HAVING clause.

For example, the following query uses

  1. A WHERE clause to filter the rows from those whose salary is less than $50000
  2. A GROUP BY clause to group the remaining rows by the city column
  3. A HAVING clause to filter the row groups to those whose average salary is greater than $30000



   <source lang="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_DAT END_DATE SALARY CITY DESCRIPTION


---------- ---------- --------- --------- ---------- ---------- ---------------

01 Jason Martin 25-JUL-96 25-JUL-06 1234.56 Toronto Programmer 02 Alison Mathews 21-MAR-76 21-FEB-86 6661.78 Vancouver Tester 03 James Smith 12-DEC-78 15-MAR-90 6544.78 Vancouver Tester 04 Celia Rice 24-OCT-82 21-APR-99 2344.78 Vancouver Manager 05 Robert Black 15-JAN-84 08-AUG-98 2334.78 Vancouver Tester 06 Linda Green 30-JUL-87 04-JAN-96 4322.78 New York Tester 07 David Larry 31-DEC-90 12-FEB-98 7897.78 New York Manager 08 James Cat 17-SEP-96 15-APR-02 1232.78 Vancouver Tester 8 rows selected. SQL> SQL> SQL> SELECT city, AVG(salary)

 2  FROM employee
 3  WHERE salary < 50000
 4  GROUP BY city
 5  HAVING AVG(salary) > 30000;

no rows selected SQL> SQL> SQL> -- clean the table SQL> drop table Employee

 2  /

Table dropped. SQL> SQL></source>