Oracle PL/SQL/Aggregate Functions/AVG
Содержание
- 1 Average Price Per Department
- 2 Average Price Per Departments Having More Than 3 Products
- 3 Average salary in Toronto: AVG with where clause
- 4 AVG(DISTINCT salary)
- 5 AVG function and NULLs
- 6 AVG: returns the average of all NOT NULL values passed into the function
- 7 Employees whose salary is more than average salary
- 8 Employees whose salary is more than average salary(use having clause only)
- 9 find the average of the uniquely priced cars: use the DISTINCT modifier:
- 10 GROUP BY clause and AVG() function
- 11 Having with avg
- 12 Syntax: AVG ([DISTINCT]|[ALL] <numeric expression>)
- 13 To find out the average price for each manufacturer: use the GROUP BY clause
- 14 Use avg and nvl together
- 15 Use NVL in set statement
Average Price Per Department
<source lang="sql">
SQL> SQL> CREATE TABLE Department (
2 DepartmentID INT NOT NULL PRIMARY KEY, 3 Name VARCHAR(50) NOT NULL, 4 Description VARCHAR(200) NULL);
SQL> SQL> CREATE SEQUENCE DepartmentIDSeq; SQL> SQL> CREATE OR REPLACE TRIGGER DepartmentAutonumberTrigger
2 BEFORE INSERT ON Department 3 FOR EACH ROW 4 BEGIN 5 SELECT DepartmentIDSeq.NEXTVAL 6 INTO :NEW.DepartmentID FROM DUAL; 7 END; 8 /
SQL> SQL> INSERT INTO Department (Name, Description) VALUES ("Software", "Coding"); SQL> INSERT INTO Department (Name, Description) VALUES ("Hardware", "Building"); SQL> INSERT INTO Department (Name, Description) VALUES ("QA", "Testing"); SQL> SQL> SQL> SQL> SQL> CREATE TABLE Category (
2 CategoryID INT NOT NULL PRIMARY KEY, 3 DepartmentID INT NOT NULL, 4 Name VARCHAR(50) NOT NULL, 5 Description VARCHAR (200) NULL);
SQL> SQL> CREATE SEQUENCE CategoryIDSeq; SQL> SQL> CREATE OR REPLACE TRIGGER CategoryAutonumberTrigger
2 BEFORE INSERT ON Category 3 FOR EACH ROW 4 BEGIN 5 SELECT CategoryIDSeq.NEXTVAL 6 INTO :NEW.CategoryID FROM DUAL; 7 END; 8 /
SQL> INSERT INTO Category (DepartmentID, Name, Description)
2 VALUES (1, "Local", "In town");
SQL> INSERT INTO Category (DepartmentID, Name, Description)
2 VALUES (1, "Remote", "Telecommute");
SQL> INSERT INTO Category (DepartmentID, Name, Description)
2 VALUES (2, "Masks", "By bits");
SQL> INSERT INTO Category (DepartmentID, Name, Description)
2 VALUES (3, "Wireless", "Not connected");
SQL> INSERT INTO Category (DepartmentID, Name, Description)
2 VALUES (3, "Wired", "Connected");
SQL> SQL> SQL> SQL> 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);
SQL> SQL> CREATE SEQUENCE ProductIDSeq; 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 /
SQL> SQL> INSERT INTO Product (Name, Description, Price, ImagePath,soldout, Promotion)
2 VALUES ("Pen", "Ball Pen",5.99, "pen.jpg", 1, 0);
SQL> SQL> INSERT INTO Product (Name, Description, Price, ImagePath, soldout, Promotion)
2 VALUES ("Ruler","Long",14.99, "ruler.jpg", 0, 0);
SQL> SQL> INSERT INTO Product (Name, Description, Price, ImagePath, soldout, Promotion)
2 VALUES ("Desk", "Computer Desk",5.99, "desk.jpg", 0, 1);
SQL> SQL> INSERT INTO Product (Name, Description, Price, ImagePath, soldout, Promotion)
2 VALUES ("PC", "Notebook",49.99, "pc.jpg", 0, 1);
SQL> SQL> INSERT INTO Product (Name, Description, Price, ImagePath, soldout, Promotion)
2 VALUES ("Mouse", "Wireless",9.99, "mouse.jpg", 1, 0);
SQL> SQL> INSERT INTO Product (Name, Description, Price, ImagePath, soldout, Promotion)
2 VALUES ("Keyboard","keyboard",3.75, "keyboard.jpg", 0, 0);
SQL> SQL> SQL> SQL> SQL> CREATE TABLE ProductCategory (
2 ProductID INT NOT NULL, 3 CategoryID INT NOT NULL, 4 PRIMARY KEY (ProductID, CategoryID) 5 );
SQL> SQL> SQL> INSERT INTO ProductCategory (ProductID, CategoryID) VALUES (1,3); SQL> INSERT INTO ProductCategory (ProductID, CategoryID) VALUES (2,1); SQL> INSERT INTO ProductCategory (ProductID, CategoryID) VALUES (2,3); SQL> INSERT INTO ProductCategory (ProductID, CategoryID) VALUES (3,3); SQL> INSERT INTO ProductCategory (ProductID, CategoryID) VALUES (4,1); SQL> INSERT INTO ProductCategory (ProductID, CategoryID) VALUES (5,2); SQL> INSERT INTO ProductCategory (ProductID, CategoryID) VALUES (6,3); SQL> INSERT INTO ProductCategory (ProductID, CategoryID) VALUES (6,4); SQL> INSERT INTO ProductCategory (ProductID, CategoryID) VALUES (7,4); SQL> INSERT INTO ProductCategory (ProductID, CategoryID) VALUES (8,5); SQL> SQL> SQL> SELECT Department.Name AS "Department",
2 AVG(Product.Price) AS "Average Price" 3 FROM Product 4 INNER JOIN ProductCategory 5 ON Product.ProductID = ProductCategory.ProductID 6 INNER JOIN Category 7 ON ProductCategory.CategoryID = Category.CategoryID 8 INNER JOIN Department 9 ON Category.DepartmentID = Department.DepartmentID 10 GROUP BY Department.Name;
Hardware
7.68
QA
3.75
Software
24.99
SQL> SQL> drop table department; SQL> drop sequence DepartmentIDSeq; SQL> drop table Product; SQL> drop table ProductCategory; SQL> drop table Category; SQL> drop sequence CategoryIDSeq; SQL> drop sequence ProductIDSeq;
</source>
Average Price Per Departments Having More Than 3 Products
<source lang="sql">
SQL> SQL> CREATE TABLE Department (
2 DepartmentID INT NOT NULL PRIMARY KEY, 3 Name VARCHAR(50) NOT NULL, 4 Description VARCHAR(200) NULL);
SQL> SQL> CREATE SEQUENCE DepartmentIDSeq; SQL> SQL> CREATE OR REPLACE TRIGGER DepartmentAutonumberTrigger
2 BEFORE INSERT ON Department 3 FOR EACH ROW 4 BEGIN 5 SELECT DepartmentIDSeq.NEXTVAL 6 INTO :NEW.DepartmentID FROM DUAL; 7 END; 8 /
SQL> SQL> INSERT INTO Department (Name, Description)
2 VALUES ("Software", "Coding");
SQL> INSERT INTO Department (Name, Description)
2 VALUES ("Hardware", "Building");
SQL> INSERT INTO Department (Name, Description)
2 VALUES ("QA", "Testing");
SQL> SQL> SQL> SQL> SQL> CREATE TABLE Category (
2 CategoryID INT NOT NULL PRIMARY KEY, 3 DepartmentID INT NOT NULL, 4 Name VARCHAR(50) NOT NULL, 5 Description VARCHAR (200) NULL);
SQL> SQL> CREATE SEQUENCE CategoryIDSeq; SQL> SQL> CREATE OR REPLACE TRIGGER CategoryAutonumberTrigger
2 BEFORE INSERT ON Category 3 FOR EACH ROW 4 BEGIN 5 SELECT CategoryIDSeq.NEXTVAL 6 INTO :NEW.CategoryID FROM DUAL; 7 END; 8 /
SQL> INSERT INTO Category (DepartmentID, Name, Description)
2 VALUES (1, "Local", "In town");
SQL> INSERT INTO Category (DepartmentID, Name, Description)
2 VALUES (1, "Remote", "Telecommute");
SQL> INSERT INTO Category (DepartmentID, Name, Description)
2 VALUES (2, "Masks", "By bits");
SQL> INSERT INTO Category (DepartmentID, Name, Description)
2 VALUES (3, "Wireless", "Not connected");
SQL> INSERT INTO Category (DepartmentID, Name, Description)
2 VALUES (3, "Wired", "Connected");
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);
SQL> SQL> CREATE SEQUENCE ProductIDSeq; 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 /
SQL> SQL> INSERT INTO Product (Name, Description, Price, ImagePath,soldout, Promotion)
2 VALUES ("Pen", "Ball Pen",5.99, "pen.jpg", 1, 0);
SQL> SQL> INSERT INTO Product (Name, Description, Price, ImagePath, soldout, Promotion)
2 VALUES ("Ruler","Long",14.99, "ruler.jpg", 0, 0);
SQL> SQL> INSERT INTO Product (Name, Description, Price, ImagePath, soldout, Promotion)
2 VALUES ("Desk", "Computer Desk",5.99, "desk.jpg", 0, 1);
SQL> SQL> INSERT INTO Product (Name, Description, Price, ImagePath, soldout, Promotion)
2 VALUES ("PC", "Notebook",49.99, "pc.jpg", 0, 1);
SQL> SQL> INSERT INTO Product (Name, Description, Price, ImagePath, soldout, Promotion)
2 VALUES ("Mouse", "Wireless",9.99, "mouse.jpg", 1, 0);
SQL> SQL> INSERT INTO Product (Name, Description, Price, ImagePath, soldout, Promotion)
2 VALUES ("Keyboard","keyboard",3.75, "keyboard.jpg", 0, 0);
SQL> SQL> SQL> CREATE TABLE ProductCategory (
2 ProductID INT NOT NULL, 3 CategoryID INT NOT NULL, 4 PRIMARY KEY (ProductID, CategoryID) 5 );
SQL> SQL> SQL> INSERT INTO ProductCategory (ProductID, CategoryID) VALUES (1,3); SQL> INSERT INTO ProductCategory (ProductID, CategoryID) VALUES (2,1); SQL> INSERT INTO ProductCategory (ProductID, CategoryID) VALUES (2,3); SQL> INSERT INTO ProductCategory (ProductID, CategoryID) VALUES (3,3); SQL> INSERT INTO ProductCategory (ProductID, CategoryID) VALUES (4,1); SQL> INSERT INTO ProductCategory (ProductID, CategoryID) VALUES (5,2); SQL> INSERT INTO ProductCategory (ProductID, CategoryID) VALUES (6,3); SQL> INSERT INTO ProductCategory (ProductID, CategoryID) VALUES (6,4); SQL> INSERT INTO ProductCategory (ProductID, CategoryID) VALUES (7,4); SQL> INSERT INTO ProductCategory (ProductID, CategoryID) VALUES (8,5); SQL> SQL> SQL> SELECT Department.Name AS "Department",
2 COUNT(Product.Name) AS "Products", 3 AVG(Product.Price) AS "Average Price" 4 FROM Product 5 INNER JOIN ProductCategory 6 ON Product.ProductID = ProductCategory.ProductID 7 INNER JOIN Category 8 ON ProductCategory.CategoryID = Category.CategoryID 9 INNER JOIN Department 10 ON Category.DepartmentID = Department.DepartmentID 11 GROUP BY Department.Name 12 HAVING COUNT(Product.Price)>=3 13 ORDER BY AVG(Product.Price) DESC;
Software
3 24.99
Hardware
4 7.68
SQL> SQL> SQL> drop table department; SQL> drop sequence DepartmentIDSeq; SQL> drop table Product; SQL> drop table ProductCategory; SQL> drop table Category; SQL> drop sequence CategoryIDSeq; SQL> drop sequence ProductIDSeq;
</source>
Average salary in Toronto: AVG with where clause
<source lang="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> -- Average salary in Toronto, SQL> SQL> SELECT AVG(Salary) AS "AVG Salary" FROM Employee WHERE City ="Toronto"; AVG Salary
1234.56
SQL> SQL> -- clean the table SQL> drop table Employee
2 /
Table dropped. SQL> SQL> SQL> SQL>
</source>
AVG(DISTINCT salary)
<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> SQL> SELECT AVG(DISTINCT salary)
2 FROM employee;
AVG(DISTINCTSALARY)
4071.7525
SQL> SQL> SQL> -- clean the table SQL> drop table Employee
2 /
Table dropped. SQL> SQL>
</source>
AVG function and NULLs
<source lang="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"), NULL ,"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"), NULL ,"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 New York Tester 07 David Larry 31-DEC-90 12-FEB-98 New York Manager 08 James Cat 17-SEP-96 15-APR-02 1232.78 Vancouver Tester 8 rows selected. SQL> SQL> SQL> --AVG function and NULLs SQL> SQL> SELECT AVG(Salary) as AVG_SAL FROM Employee;
AVG_SAL
3392.24333 SQL> SQL> SQL> -- clean the table SQL> drop table Employee
2 /
Table dropped. SQL> SQL> SQL>
</source>
AVG: returns the average of all NOT NULL values passed into the function
<source lang="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> SQL> SQL> SQL> SQL> SQL> --AVG: returns the average of all NOT NULL values passed into the function SQL> --It only accepts numeric datatype values SQL> SQL> select AVG(Salary) from Employee; AVG(SALARY)
4071.7525
SQL> SQL> SQL> -- clean the table SQL> drop table Employee
2 /
Table dropped. SQL> SQL>
</source>
Employees whose salary is more than average salary
<source lang="sql">
SQL> create table emp
2 ( empno NUMBER(4) constraint E_PK primary key 3 , ename VARCHAR2(8) 4 , init VARCHAR2(5) 5 , job VARCHAR2(8) 6 , mgr NUMBER(4) 7 , bdate DATE 8 , sal NUMBER(6,2) 9 , comm NUMBER(6,2) 10 , deptno NUMBER(2) default 10 11 ) ;
Table created. SQL> insert into emp values(1,"Tom","N", "TRAINER", 13,date "1965-12-17", 800 , NULL, 20); 1 row created. SQL> insert into emp values(2,"Jack","JAM", "Tester",6,date "1961-02-20", 1600, 300, 30); 1 row created. SQL> insert into emp values(3,"Wil","TF" , "Tester",6,date "1962-02-22", 1250, 500, 30); 1 row created. SQL> insert into emp values(4,"Jane","JM", "Designer", 9,date "1967-04-02", 2975, NULL, 20); 1 row created. SQL> insert into emp values(5,"Mary","P", "Tester",6,date "1956-09-28", 1250, 1400, 30); 1 row created. SQL> insert into emp values(6,"Black","R", "Designer", 9,date "1963-11-01", 2850, NULL, 30); 1 row created. SQL> insert into emp values(7,"Chris","AB", "Designer", 9,date "1965-06-09", 2450, NULL, 10); 1 row created. SQL> insert into emp values(8,"Smart","SCJ", "TRAINER", 4,date "1959-11-26", 3000, NULL, 20); 1 row created. SQL> insert into emp values(9,"Peter","CC", "Designer",NULL,date "1952-11-17", 5000, NULL, 10); 1 row created. SQL> insert into emp values(10,"Take","JJ", "Tester",6,date "1968-09-28", 1500, 0, 30); 1 row created. SQL> insert into emp values(11,"Ana","AA", "TRAINER", 8,date "1966-12-30", 1100, NULL, 20); 1 row created. SQL> insert into emp values(12,"Jane","R", "Manager", 6,date "1969-12-03", 800 , NULL, 30); 1 row created. SQL> insert into emp values(13,"Fake","MG", "TRAINER", 4,date "1959-02-13", 3000, NULL, 20); 1 row created. SQL> insert into emp values(14,"Mike","TJA","Manager", 7,date "1962-01-23", 1300, NULL, 10); 1 row created. SQL> SQL> select e.empno
2 from emp e
3 where e.sal > (select avg(x.sal)
4 from emp x);
EMPNO
4
6
7
8
9
13
6 rows selected. SQL> SQL> SQL> drop table emp; Table dropped. SQL>
</source>
Employees whose salary is more than average salary(use having clause only)
<source lang="sql">
SQL> create table emp
2 ( empno NUMBER(4) constraint E_PK primary key 3 , ename VARCHAR2(8) 4 , init VARCHAR2(5) 5 , job VARCHAR2(8) 6 , mgr NUMBER(4) 7 , bdate DATE 8 , sal NUMBER(6,2) 9 , comm NUMBER(6,2) 10 , deptno NUMBER(2) default 10 11 ) ;
Table created. SQL> insert into emp values(1,"Tom","N", "TRAINER", 13,date "1965-12-17", 800 , NULL, 20); 1 row created. SQL> insert into emp values(2,"Jack","JAM", "Tester",6,date "1961-02-20", 1600, 300, 30); 1 row created. SQL> insert into emp values(3,"Wil","TF" , "Tester",6,date "1962-02-22", 1250, 500, 30); 1 row created. SQL> insert into emp values(4,"Jane","JM", "Designer", 9,date "1967-04-02", 2975, NULL, 20); 1 row created. SQL> insert into emp values(5,"Mary","P", "Tester",6,date "1956-09-28", 1250, 1400, 30); 1 row created. SQL> insert into emp values(6,"Black","R", "Designer", 9,date "1963-11-01", 2850, NULL, 30); 1 row created. SQL> insert into emp values(7,"Chris","AB", "Designer", 9,date "1965-06-09", 2450, NULL, 10); 1 row created. SQL> insert into emp values(8,"Smart","SCJ", "TRAINER", 4,date "1959-11-26", 3000, NULL, 20); 1 row created. SQL> insert into emp values(9,"Peter","CC", "Designer",NULL,date "1952-11-17", 5000, NULL, 10); 1 row created. SQL> insert into emp values(10,"Take","JJ", "Tester",6,date "1968-09-28", 1500, 0, 30); 1 row created. SQL> insert into emp values(11,"Ana","AA", "TRAINER", 8,date "1966-12-30", 1100, NULL, 20); 1 row created. SQL> insert into emp values(12,"Jane","R", "Manager", 6,date "1969-12-03", 800 , NULL, 30); 1 row created. SQL> insert into emp values(13,"Fake","MG", "TRAINER", 4,date "1959-02-13", 3000, NULL, 20); 1 row created. SQL> insert into emp values(14,"Mike","TJA","Manager", 7,date "1962-01-23", 1300, NULL, 10); 1 row created. SQL> SQL> select e1.empno
2 from emp e1
3 , emp e2
4 group by e1.empno
5 , e1.sal
6 having e1.sal > avg(e2.sal);
EMPNO
4
6
7
8
9
13
6 rows selected. SQL> SQL> SQL> SQL> drop table emp; Table dropped.
</source>
find the average of the uniquely priced cars: use the DISTINCT modifier:
<source lang="sql">
SQL> SQL> CREATE TABLE cars
2 ( 3 MAKER VARCHAR (25), 4 MODEL VARCHAR (25), 5 PRICE NUMERIC 6 );
Table created. SQL> SQL> INSERT INTO CARS VALUES("CHRYSLER","CROSSFIRE",33620); 1 row created. SQL> INSERT INTO CARS VALUES("CHRYSLER","300M",29185); 1 row created. SQL> INSERT INTO CARS VALUES("HONDA","CIVIC",15610); 1 row created. SQL> INSERT INTO CARS VALUES("HONDA","ACCORD",19300); 1 row created. SQL> SQL> INSERT INTO CARS VALUES("FORD","MUSTANG",15610); 1 row created. SQL> INSERT INTO CARS VALUES("FORD","LATESTnGREATEST",NULL); 1 row created. SQL> INSERT INTO CARS VALUES("FORD","FOCUS",13005); 1 row created. SQL> SQL> SQL> SQL> SELECT
2 AVG(DISTINCT price) average_price 3 FROM cars;
SQL> SQL> drop table cars; Table dropped. SQL>
</source>
GROUP BY clause and AVG() function
<source lang="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> SQL> -- GROUP BY clause and AVG() function SQL> SQL> SELECT city, AVG(salary)
2 FROM employee 3 GROUP BY city;
CITY AVG(SALARY)
-----------
New York 6110.28 Toronto 1234.56 Vancouver 3823.78 SQL> SQL> SQL> SQL> SQL> -- clean the table SQL> drop table Employee
2 /
Table dropped. SQL> SQL>
</source>
Having with avg
<source lang="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 to_char(order_date, "YYYY/MM") "Month",
2 avg(total_order_price) "Avg Sales by Month" 3 from ord 4 group by to_char(order_date, "YYYY/MM") 5 having avg(total_order_price) > 35;
Month Avg Sales by Month
------------------
2003/02 510.98 2004/02 315.99 2002/03 101.95 2008/06 190.9625 1999/02 191.95 2003/04 221.95 2004/06 315.95 2003/12 715.95 1999/12 135.95 9 rows selected. SQL> SQL> SQL> drop table ord; Table dropped. SQL> --
</source>
Syntax: AVG ([DISTINCT]|[ALL] <numeric expression>)
<source lang="sql">
SQL> SQL> SQL> SQL> CREATE TABLE cars
2 ( 3 MAKER VARCHAR (25), 4 MODEL VARCHAR (25), 5 PRICE NUMERIC 6 );
Table created. SQL> SQL> INSERT INTO CARS VALUES("CHRYSLER","CROSSFIRE",33620); 1 row created. SQL> INSERT INTO CARS VALUES("CHRYSLER","300M",29185); 1 row created. SQL> INSERT INTO CARS VALUES("HONDA","CIVIC",15610); 1 row created. SQL> INSERT INTO CARS VALUES("HONDA","ACCORD",19300); 1 row created. SQL> SQL> INSERT INTO CARS VALUES("FORD","MUSTANG",15610); 1 row created. SQL> INSERT INTO CARS VALUES("FORD","LATESTnGREATEST",NULL); 1 row created. SQL> INSERT INTO CARS VALUES("FORD","FOCUS",13005); 1 row created. SQL> SQL> gather some statistical information about the cars in the CARS table SQL> SQL> SELECT
2 AVG(price) average_price 3 FROM cars;
SQL> SQL> SQL> SQL> drop table cars; Table dropped. SQL>
</source>
To find out the average price for each manufacturer: use the GROUP BY clause
<source lang="sql">
SQL> SQL> CREATE TABLE cars
2 ( 3 MAKER VARCHAR (25), 4 MODEL VARCHAR (25), 5 PRICE NUMERIC 6 );
Table created. SQL> SQL> INSERT INTO CARS VALUES("CHRYSLER","CROSSFIRE",33620); 1 row created. SQL> INSERT INTO CARS VALUES("CHRYSLER","300M",29185); 1 row created. SQL> INSERT INTO CARS VALUES("HONDA","CIVIC",15610); 1 row created. SQL> INSERT INTO CARS VALUES("HONDA","ACCORD",19300); 1 row created. SQL> SQL> INSERT INTO CARS VALUES("FORD","MUSTANG",15610); 1 row created. SQL> INSERT INTO CARS VALUES("FORD","LATESTnGREATEST",NULL); 1 row created. SQL> INSERT INTO CARS VALUES("FORD","FOCUS",13005); 1 row created. SQL> SQL> SQL> SELECT
2 maker, 3 AVG(price) average_price 4 FROM cars 5 GROUP BY maker;
SQL> SQL> drop table cars; Table dropped. SQL> SQL>
</source>
Use avg and nvl together
<source lang="sql">
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 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
Page 1
EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
---------- --------- ---------- --------- ---------- ---------- ----------
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 MILLER CLERK 7782 23-JAN-82 1300 10
Page 2
14 rows selected. SQL> SQL> SQL> SQL> SELECT AVG(NVL(comm,0))
2 FROM emp;
AVG(NVL(COMM,0))
157.142857
Page 1
SQL> SQL> SQL> drop table emp; Table dropped.
</source>
Use NVL in set statement
<source lang="sql">
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 comm from emp;
COMM
300
500
1400
Page 1
COMM
0
Page 2
14 rows selected. SQL> SQL> UPDATE emp
2 SET comm = NVL(comm,0) + 10;
14 rows updated. SQL> SQL> select comm from emp;
COMM
10
310
510
10
1410
10
10
10
Page 1
COMM
10
10
10
10
10
10
Page 2
14 rows selected. SQL> SQL> SQL> drop table emp; Table dropped.
</source>
