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SQL (Standard Query Language)
Yong Choi
School of Business
CSU, Bakersfield
Study Objectives
• Understand the basic commands and functions of
SQL
• Learn how to use SQL to query a database to
extract useful information
• Practice SQL
2
Introduction to SQL
• Standard Query Language (SQL) is a computer language
for the relational database model.
• SQL is a nonprocedural language (click here for the
example). So, it is much easier to use.
– what is to be done without having to worry about how
it's to be done.
• Procedural language (click here for the example)
– Must be programmed correctly and compiled
– Java, C++, and Pascal.
• SQL is relatively easy to learn
– SQL commands set has a basic vocabulary of less than
100 words.
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3
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SQL Example
SELECT ID, L_Name, F_Name, Salary, Dept_No
FROM Employee;
ID
L_Name
F_Name
Salary
Dept_No
--------- ---------- ---------- ---------- ------------------------------------------------------------------------1
Kim
John
1000
100
2
Johnson
Steve
1200
100
3
Jonson
Paul
1100
200
4
Lee
Jim
1100
200
5
Basinger
Jon
1300
6
Stone
Sharon
1000
6 rows selected.
4
Back
JAVA Example
public class JavaProgramming
{
public static void main ( String[] args )
{
long payAmount;
payAmount = 123;
System.out.println("The variable contains: " + payAmount );
}
}
• Output: The Variable contains 123.
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Basic SQL Commands
• Followings are the most frequently used commands
– Use always
• SELECT <field list>
• FROM <table list>
– Use when conditions must be specified
• WHERE <condition>
• HAVING <group condition>
• ORDER BY <sorting field>
• GROUP BY < grouping records>
6
The SELECT and FROM Statement
• Need both commands almost always…..
– The SELECT statement is used to select data from
a table.
– The FROM statement is used to select tables.
• Syntax:
– SELECT column_name(s)
– FROM table_name
• To select all columns (fields) from a table, use *
symbol instead of column names:
– SELECT *
– FROM table_name
7
The WHERE Statement
• To conditionally select data from a table, a
WHERE clause can be added to the SELECT
statement.
• Syntax:
– SELECT column
– FROM table
– WHERE column operator value
• See next slide for various operators
8
SQL Comparison Operators FOR
WHERE clause
AND logical operator
OR logical operator
NOT Warehouse =‘3’
LIKE: LIKE ‘a*’, LIKE ‘*s’, Like ‘*Oxford*’
BETWEEN 45000 AND 78000
9
Semicolon after SQL Statements?
• Semicolon is the standard way to a block of SQL
statement in database systems. So, you must use a
semicolon at the end of a block of SQL statement.
– Access SQL commands are not case sensitive but
try to follow exact names for better readability.
• Download SQL data file form the class web site.
– SQL_300.mdb
10
Customer
CustomerNum
CustomerName
Street
City
State
Zip
Balance
148
Al's Appliance and
Sport
2837
Greenway
Fillmore
FL
33336
$6,550
CreditLimit
$7,500
RepNum
20
OrderLine
OrderNum
PartNum
21608
AT94
NumOrdered
QuotedPrice
11
$21.95
Orders
OrderNum
21608
OrderDate
10/20/2003
CustomerNum
148
Part
PartNum
Description
AT94
Iron
OnHand
50
Class
Warehouse
HW
3
Price
$24.95
Rep
RepNum
LastName
FirstName
Street
City
State
Zip
20
Kaiser
Valerie
624 Randall
Grove
FL
33321
Commission
$20,542.50
Rate
0.05
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SQL Preparation
• Review tables and relationships first…
– Review each table in both views
• Design view
• Datasheet view
– Recognize PK and FK information
– Examine Relationships information
• SQL using Access
– Design view of query  Select SQL View using
Style button
– No need to add tables (unlike QBE)
12
SQL Sample
• I’d like to know the list of CustomerNum and
CustomerName.
– SELECT CustomerNum, CustomerName
– FROM Customer;
• I’d like to know the list of PartNum, Description,
RepNum, and LastName
– SELECT PartNum, Description, RepNum, LastName
– FROM Part, Rep;
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SQL Example 1 & 2
• Example 1:
– I’d like to know a list of the Customer number,
Customer name, and balance of all customers.
– Save as SQL 1
• Example 2:
– I’d like to know a list of the Order number, Part
number, Price and Order Date.
– Save as SQL 2
14
SQL Example 3
• Restriction requirements
– Where command
– Exact Match
• Example 3:
– I’d like to know customer names who are located
in the city of Grove
– Save as SQL 3
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SQL Query to Find
All Customers in ‘Grove’
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SQL Example 4
• Restriction requirements
– Where command
– Comparison operator
• Example 4:
– I’d like to know a list of the number, name, credit
limit, and balance for customers with credit limits
that exceed their balances.
– Save as SQL 4
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Query to find Customers with Credit
Limit Exceeding Balance
18
SQL Example 5
• Restriction requirements
– Where command
– Compound conditions
• Example 5:
– List the description of all parts that are located in
warehouse 3 and for which there are more than 20
units on hand.
– Save as SQL 5
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SQL Query with Compound
Condition using ‘AND’
20
SQL Example 6
• Default value of ORDER BY: ascending
• Example 6:
– List the number, name, and credit limit of all customers.
Sort the customers by name in ascending order.
– Save as SQL 6
21
SQL Query to Sort Data
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