STRUCTURED QUERY LANGUAGE (SQL) Chapter 5: Part 2: DML

STRUCTURED QUERY LANGUAGE (SQL)

Chapter 5:Part 2:DML

Objectives2

To be able to apply SQL command. How to use DML in SQL

2 major components:1. Data Definition Language (DDL)

defining database structure. allows database objects such as schemas, domains,

tables, views and indexes to be created and destroyed.

2. Data Manipulation Language (DML) retrieving and updating data. used to populate and query the tables. data manipulation.

Data Manipulation LanguageManipulate data

DML3

Data Manipulation Language(DML)4

Data Manipulation in SQL is an ability for manipulating the data to provide information needs by

users.

Manipulating the data referees to process of: selecting the data do some operation at the data user view it or save it in the database

SELECT * FROM printerWHERE color = ‘red’ OR color = ‘blue’;

DML: Queries: SELECT Statement5

SELECT Statement The SELECT statement allows you to find, retrieve, and

display data.

To execute the SELECT statement on a table, you must be the table owner, have DBA or SYSADM security privileges, or have the SELECT privilege for that table.

The result of SELECT statement is a set of rows known as the result set, which meets the conditions specified in the SELECT statement

SQL SELECT Syntax

Note

SQL is not case sensitive { SELECT is the same as select }

SELECT column_name(s)FROM table_name;

SELECT *FROM table_name;

DML: Queries: SELECT Statement6

printerNO description color price

P123 Dot-matrix Red 249.56

HP874 Laser Jet Blue 559.99

Select all data from table printer.

Select printerNO and price from table printer.

SELECT *FROM printer;

SELECT printerNO, priceFROM printer;

printerNO

price

P123 249.56

HP874 559.99

DML: Queries: SELECT DISTINCT Statement

7

SELECT DISTINCT Statement In a table, some of the columns may contain duplicate

values. The DISTINCT keyword can be used to return only distinct

(different) values.

SQL SELECT DISTINCT SyntaxSELECT DISTINCT column_name(s)FROM table_name;

DML: Queries: SELECT DISTINCT Statement

8

The following statement only will select the distinct values from the column named city from table staff.

SELECT DISTINCT cityFROM staff;

staffNO staffNAME city

ABC987 Nadz Kuala Lumpur

ABC988 Aina Jerantut

ABC999 Halimaton Jerantut

city

Kuala Lumpur

Jerantut

SQL LIKE Operator9

The LIKE operator is used in a WHERE statement to search for a specified pattern in a column.

SQL LIKE Syntax

Note

The LIKE operator is commonly used with SQL Wildcards

SELECT column_name(s)FROM table_nameWHERE column_name LIKE patern;

SQL LIKE Operator10



SELECT *FROM staffWHERE city LIKE “K%”;

The following select staffs living in a city start with “K” from table ‘staff’.

SQL Wildcards11

SQL wildcards can be used when searching for data in a database.

SQL wildcards can substitute for one or more characters when searching for data in a database.

SQL wildcards must be used with the SQL LIKE operator. With SQL, the following wildcards can be used:Wildcard Description

% A substitute for zero or more characters

_ A substitute for exactly one character

[charlist] Any single character in charlist

[^charlist] or[!charlist]

Any single character not in charlist

Wildcards: Using The % Wildcard

12

Select staff living in the city that start with ‘La’ from staff table.

Select staff living in the city that contain pattern ‘wi’ from staff table.

SELECT *FROM staffWHERE city LIKE "La%";

SELECT *FROM staffWHERE city LIKE "%wi%";

Wildcards: Using The _ Wildcard

13

Select staff with a name that starts with any character, followed by ‘da’ from staff table.

Select staff with a name that starts with "S", followed by any character, followed by "ar", followed by any character, followed by "s" from staff table.

SELECT *FROM staffWHERE staffNAME LIKE "_da";

SELECT *FROM staffWHERE staffNAME LIKE "S_ar_s";

Wildcards: Using The [charlist] Wildcard

14

Select staff with a name that starts with "a" or "s" or "p" from staff table.

Select staff name that do not starts with “"a" or "s" or "p" from staff table.

SELECT *FROM staffWHERE staffNAME LIKE "[asp]%";

SELECT *FROM staffWHERE staffNAME LIKE "[!asp]%";

DML: Data Entry15

The INSERT INTO command inserts new rows into a table.

When you insert data into a child table that has a foreign key linking it to a parent table, you must obey referential integrity rules.

This means you cannot insert a value into a child key that does not exist in the parent key unless it is a NULL value.

You must insert a new row into the parent key first.

To insert a string that contains a single quote, you must replace the single quote in the string with two consecutive single quotes.

DML: Data Entry16

SQL INSERT INTO Syntax It is possible to write the INSERT INTO statement in two

forms. The first form doesn't specify the column names where the

data will be inserted, only their values:

The second form specifies both the column names and the values to be inserted:

INSERT INTO table_nameVALUES (value1, value2,…);

INSERT INTO table_name (column1,column2,…)VALUES (value1, value2,…);

DML: Data Entry17


ABC123 Norain Ipoh

The following insert values into table ‘staff’.

INSERT INTO staff VALUES (‘ABC123’, ‘Norain', ‘Ipoh’);

DML: Data Entry18

Insert a new customer for the following table.

insert into tblcustomer (customerno, customername, customeremail)values (‘C001’, ‘Alya Qiesya’, ‘[email protected]’);

DML: Deleting Table Rows19

The DELETE command deletes all rows matching the search condition from a table.

You can only delete rows from a single table, and you cannot delete rows from the system tables.

To execute the DELETE command, you must be the table owner, have delete privilege on the table, or have DBA or SYSADM security privileges.

DML: Deleting Table Rows 20

SQL DELETE Syntax

Note

Notice the WHERE clause in the DELETE syntax. The WHERE clause

specifies which record or records that should be deleted. If you omit the

WHERE clause, all records will be deleted!

DELETE FROM table_nameWHERE some column=some value

DML: Deleting Table Rows21

DELETE record as specified in WHERE clause.

The following example deletes all staff whose name begins with “Muhammad" from the staff table.

The following example deletes staff number ABC125 from the staff table.

DELETE FROM staffWHERE staffNO=“ABC123” AND city=“Ipoh”;

DELETE FROM staffWHERE staffNAME LIKE “Muhammad%”;

DELETE FROM staffWHERE staffNO =“ABC125”;

DML: Making Changes to Data Items

22

The UPDATE command updates existing rows in a table.

When you update a column, the new column values must satisfy the column constraints and referential integrity.

If the column has a DEFAULT value defined, you can use the DEFAULT keyword to set the value of the column to the default value.


23

SQL UPDATE Syntax

Note

Notice the WHERE clause in the UPDATE syntax. The WHERE clause specifies which record or records that should be updated. If you omit the WHERE clause, all records will be updated!

UPDATE table_nameSET column1=value,column2=value2,…WHERE some column=some value


24

Shows how to update the staff table and change the city value for staff named “Rosliza".

Shows how to give a salary raise of 5% to staff named “Wafiy".

Update description for printer with printerNO F380.

UPDATE staffSET city=“Bangi”WHERE staffNAME = “Rosliza”;

UPDATE staffSET salary=salary*1.05WHERE staffNAME = “Wafiy”;

UPDATE printerSET description=“KO”WHERE printerNO = “F380”;

DML: COMMIT25

The COMMIT statement terminates the current transaction and makes all

changes under the transaction persistent.

COMMIT is used for saving the data that has been changed permanently because whenever you perform any DML like UPDATE, INSERT or DELETE then you are required to write COMMIT at the end of all or every DML operation in order to save it permanently.

If you do not write COMMIT and your program crashes then your data will be restored into its previous condition.

The COMMIT statement has the following general format:UPDATE printer SET indate = ‘15/01/2007'

WHERE printerNO = 'F380'; COMMIT;

DML: ROLLBACK26

The ROLLBACK statement terminates the current transaction and cancel all changes made under the transaction.

ROLLBACK is used if you want to restore your data into its previous condition.

ROLLBACK can be write at any time after the DML queries has been written but remember once COMMIT has been written then you cannot rollback the data.

You can only rollback the DML queries that have been written after the last commit statement.

The ROLLBACK statement has the following general format:

INSERT INTO staffVALUES (“ABC990”, “Shafiza”, “Johor”)

ROLLBACK;

DML: COMMIT & ROLLBACK27

The concept of COMMIT and ROLLBACK is designed for data consistency

because many uses manipulate data of the same table, using the same

database so the user must get updated data. That is why COMMIT and

ROLLBACK are used for.

COMMIT to save whatever has been done. It is used to permanently store it in memory.

ROLLBACKto undo something. If we use roll-back, the particular changes made are undone.

DML: Compound Statement with SELECT

28

Symbol

Meaning

= Equal to

< Less than

<= Less than or equal to

> Greater than

>= Greater than or equal to

<> Not equal to*

*Some SQL version use !=

ANDto combine two search conditions which must be both true.

ORto combine two search conditions when one or the other (or both) must be true

You can combine simple conditions with the logical operators

AND, OR, and NOT to form compound conditions.


29

Select only the staff live in Jengka AND age greater then or equal to 40 years old from table staff.

Select only the staff live in Temerloh OR age greater then or equal to 40 years old from table staff.

SELECT *FROM staffWHERE city=“Jengka” AND age >= 40;

SELECT *FROM staffWHERE city=“Temerloh” AND age >= 40;


30

Select only the staff live in Jengka OR Temerloh AND age greater then or equal to 40 years old from table staff.

SELECT *FROM staffWHERE (city=“Jengka” OR city=“Temerloh”) AND age >= 40;

Do it!31

Delete all biscuits with chocolate flavor from tblbiscuit.

Delete all order from customerC001 that have status cancel from tblorder.

delete from tblbiscuitwhere bisFLAVOUR = “chocolate”;

delete from tblorderwhere custNO = “C001” and status = “cancel”;

tblcustomer(custNO, custNAME, custEMAIL)tblbiscuit(bisNO, bisNAME, bisFLAVOUR, bisPRICE)tblorder(orderNO,*custNO,*bisNO, orderadate, qty, status)

32

Change all status to confirm for biscuit BIS101 for customer C135.

Increase biscuit price 10% for biscuit with strawberry flavor.

update tblorderset status = “confirm”where custNO = “C135”;

update tblbiscuitset bisPRICE=bisPRICE*1.01where bisFLAVOUR = “strawberry”;


33

List down all customer name and email who order biscuit cornflakes.

List down all biscuit details being order by customer C010.

select c.custNAME, c.custEMAILfrom tblcustomer c, tblorder o, tblbiscuit bwhere c.custNO=o.custNo and o.bisNO=b.bisNo and b.bisNAME = “cornflakes”;

select b.bisNO, b.bisNAME, b.bisFLAVOUR, b.bisPRICEfrom tblbiscuit b, tblorder owhere b.bisNO=o.bisNO and o.custNO=“C010”;


SQL Alias34

You can give a table or a column another name by using an alias. This can be a good thing to do if you have very long or complex table names or column names.

An alias name could be anything, but usually it is short. Usually it is used in multiple table joint.

SQL Alias Syntax For Tables

SQL Alias Syntax For Columns

SELECT column_name(s)FROM table_nameAS alias_name

SELECT column_name AS alias_nameFROM table_name

SQL Alias35

The following statement list all the staff name that work at IT department.

staffNO

staffNAME

city salary

departNO


2300 0001

ABC988 Aina Jerantut 2500 0002

ABC989 Halimaton

Jerantut 2200 0001

ABC990 Norain Johor 2000 0003

departNO departNAME

0001 IT

0002 Network

0003 Management

staff department

SELECT s.staffNAMEFROM staff AS s, department AS dWHERE (d.departNO=s.departNO) AND d.departNAME=“IT”;

staffNAME

Nadz

Halimaton

SQL JOINs36

The JOIN keyword is used in an SQL statement to query data from two or more tables, based on a relationship between certain columns in these tables.

Tables in a database are often related to each other with keys.

A primary key is a column (or a combination of columns) with a unique value for each row. Each primary key value must be unique within the table. The purpose is to bind data together, across tables, without repeating all of the data in every table.

SQL JOINs37

Different SQL JOINs

JOIN / INNER JOIN

Return rows when there is at least one match in both tables LEFT JOIN

Return all rows from the left table, even if there are no matches in the right table

RIGHT JOIN

Return all rows from the right table, even if there are no matches in the left table

FULL JOIN

Return rows when there is a match in one of the tables

SQL INNER JOIN38

SQL INNER JOIN Syntax

NOTE

INNER JOIN is the same as JOIN.

SELECT column_name(s)FROM table_name1INNER JOIN table_name2ON table_name1.column_name = table_name2.column_name

SQL INNER JOIN39

The following statement list all the staff name that work at IT department.

staffNO

staffNAME

city salary

departNO


2300 0001

ABC988 Aina Jerantut 2500 0002

ABC989 Halimaton

Jerantut 2200 0001

ABC990 Norain Johor 2000 0003

departNO departNAME

0001 IT

0002 Network

0003 Management

staff department

SELECT staff.staffNAME,depart.departNAMEFROM staffINNER JOIN departmentON department.departNO=staff.departNO;

staffNAME

Nadz

Halimaton

DML: Two-Table Joins40

Besides INNER JOIN, you can also use the following statements to combines two tables with join conditions.

staff(staffNO, staffNAME, city, salary, departmentNO*)department(departNO, departNAME)

SELECT s.staffNAMEFROM staff AS s, department AS dWHERE (d.departNO=s.departNO) AND d.departNAME=“IT”;

SELECT staff.staffNAME,department.departNAMEFROM staffINNER JOIN departmentON department.departNO=staff.departNO;

DML: Multiple-Table Joins41

A multiple table join is a join of more than two tables with join conditions for pairs of table.

A join condition is a comparison (relational operators) on two columns from each table.

Following is a three table joins which selects all the customer name that order biscuit Tart Nenas Gunting.

customer(custNO, custNAME, custEMAIL)biscuit(bisNO, bisNAME, bisFLAVOUR, bisPRICE)order(orderNO,*custNO,*bisNO, orderadate, qty, status)

SELECT custNAMEFROM customer AS c, biscuit AS b, order AS o WHERE c.custNO=o.custNO AND o.bisNO=b.bisNO AND b.bisNAME=“Tart Nenas Gunting“;

DML: Multiple-Table Joins42

List down all customer name, biscuit name and order quantity that customer had order with confirm status.select c.custNAME,b.bisNAME,o.qtyfrom tblcustomer c, tblbiscuit b, tblorder owhere c.custNO=o.custNO and b.bisNO=o.bisNO and o.status=“Confirm”;


DML: GROUP BY Statement43

GROUP BY statement produce summary data within a group.

a group is a set of rows that have the same values of group by columns.

a single row of aggregate results is produced for each group. the column you want to group results by is identified by its

column name.

restrict what you can enter in the SELECT statement. SELECT statement in GROUP BY statement must be one of the

following: An aggregate function, which produces a single value summarizing

the rows in the group. A grouping column which is listed in the GROUP BY statement. A constant. An expression involving a combination of the above.


SQL GROUP BY Syntax

SELECT column_name(s), aggregate_function(column_name)FROM table_nameGROUP BY column_name;


The following statement will output staff average salary group by city.

staffNO staffNAME

city salary

gender departNO


2300 Male 0001

ABC988 Aina Jerantut 2500 Female 0002

ABC989 Halimaton Jerantut 2200 Female 0001

ABC990 Norain Johor 2000 Female 0003

staff

SELECT city, MIN(salary) AS minSALARYFROM staffGROUP BY city;

city minSALARY

Kuala Lumpur

2300

Jerantut 2200

Johor 2000

DML: ORDER BY Keyword46

The ORDER BY keyword is used to sort the result-set by a specified column. sort the records in ascending order by default. By default the records are in ascending order or you can used

ASC keyword If you want to sort the records in a descending order, you can

use DESC keyword. The default order is ascending. NULL values are treated as

larger that non-null values for sorting purposes.

SQL ORDER BY SyntaxSELECT column_name(s)FROM table_nameORDER BY column_name(s) ASC|DESC

DML: ORDER BY Keyword47

The following statement will output staff average salary group by city.

staffNO

staffNAME

city salary

gender

departNO


2300 Male 0001

ABC988 Aina Jerantut 2500 Female

0002

ABC989 Halimaton

Jerantut 2200 Female

0001

ABC990 Norain Johor 2000 Female

0003

staff

SELECT city, MIN(salary) AS minSALARYFROM staffGROUP BY cityORDER BY city DESC;

city minSALARY

Jerantut 2200

Johor 2000

Kuala Lumpur

2300

DML: HAVING Statement48

HAVING statement is used to select or reject a group.

The following example shows the average salary for staff based on city where the total staff salary exceeds RM 2000.

staffNO

staffNAME

city salary gender

departNO


2300 Male 0001

ABC988 Aina Jerantut 2500 Female

0002

ABC989 Halimaton

Jerantut 2200 Female

0001

ABC990 Norain Johor 2000 Female

0003

SELECT city, AVG(salary) AS avgSALARYFROM staffGROUP BY cityHAVING SUM(salary)> 2000 ;

city avgSALARY

Kuala Lumpur

2300

Jerantut 2350

SQL Aggregate Functions49

SQL aggregate functions return a single value, calculated from values in a column

COUNT( ) returns the number of rows

SUM( ) returns the sum

AVG( ) returns the average value

MIN( ) returns the smallest value

MAX( ) returns the largest value

FIRST( ) returns the first value

LAST( ) returns the last value

SQL Aggregate Functions50

Each operates on a single column of a table and returns a single value.

COUNT, MIN, and MAX apply to numeric and non-numeric fields

SUM and AVG may be used on numeric fields only.

Apart from COUNT(*), each function eliminates nulls first and operates only on remaining non-null values.

COUNT(*) counts all rows of a table, regardless of whether nulls or duplicate values occur.

Can use DISTINCT before column name to eliminate duplicates.

DISTINCT has no effect with MIN/MAX, but may have with SUM/AVG.

MIN/MAX/AVG51

penNO descr color qty

1001 Xtra-Fine Red 12

1002 Fine Blue 32

1003 Medium Pink 4

pen

SELECT MIN(qty)AS minQTY, MAX(qty) AS maxQTY, AVG(qty) AS avgQTYFROM pen;

minQTY maxQTY avgQTY

4 32 16

SUM/COUNT52



1002 Fine Blue 32

1003 Medium Pink 4

pen

SELECT SUM(qty)AS totalQTYFROM pen;

totalQTY

48

SELECT COUNT(penNO)AS penNUMBERFROM pen;

penNUMBER

3

FIRST/LAST53



1002 Fine Blue 32

1003 Medium Pink 4

pen

SELECT FIRST(color)AS firstCOLORFROM pen;

firstCOLOR

Red

SELECT LAST(color)AS lastCOLORFROM pen;

lastCOLOR

Pink

54

a. Find biscuit name that have the highest price.

b. List down all the biscuit order quantity for each biscuit type.

c. List down all the biscuit order quantity for each customer and sort according to the customer name.

d. List down how many customer order being made for each biscuit.

e. List down all customer name and email who order more then 5 biscuits.

f. List down biscuit information that never being order yet.


55

Find biscuit name that have the highest price.

SELECT bisNAMEFROM tblbiscuitWHERE bisPRICE = (SELECT MAX(bisPRICE) FROM tblbiscuit);

Documents

STRUCTURED QUERY LANGUAGE (SQL) Chapter 5: Part 2: DML