Download DB Queries

Database Queries
aka
SQL (pronounced “sequel”)
What is SQL?
SQL = Standard Query Language
SQL is a language for retrieving,
creating, modifying, or removing data
from just about any modern database
What is SQL?
To get information from a database file, a
user issues a “query”
 A “query” is a request to retrieve data
 MS Access will go through all the records
in the database and “select” those records
that satisfy the search condition
 SQL (Structured Query Language) allows a
user to specify the conditions without
writing complex code

Basic SQL Commands
Creating tables with CREATE
 Adding data with INSERT

 Viewing data with SELECT
 Removing data with DELETE
 Modifying data with UPDATE
 Destroying tables with DROP
Retrieving Data from
One Table
The SELECT
SELECT column1, column2, …
FROM tablename
{WHERE condition}
{ORDER BY column}
A few simple SELECTs

SELECT * FROM contacts;
– Display all records in the ‘contacts’ table

SELECT contactid, name FROM contacts;
– Display only the contactid and name

SELECT contactname FROM contacts
ORDER BY contactname;
– Display only the contactname, sort by name
The SELECT
ALL
Columns
SELECT *
FROM
TABLE;
End of
Command
No WHERE Clause so ALL Rows are Returned
Adapted from DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall
Refining selections with WHERE

The WHERE “clause” allows you to select
records based on a condition

SELECT * FROM contacts
WHERE age<10;
– Display records from contacts where age<10

SELECT * FROM contacts
WHERE age BETWEEN 18 AND 35;
– Display records where age is 18-35
WHERE with “AND”
SELECT
FROM
WHERE
AND
*
SALES_DATA
Department = 'Water Sports'
Buyer = 'Nancy Meyers';
Adapted from DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall
WHERE with “OR”
SELECT
FROM
WHERE
OR
*
SALES_DATA
Department = 'Camping'
Department = 'Climbing';
Adapted from DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall
WHERE with “IN”
SELECT
FROM
WHERE
*
SALES_DATA
Buyer IN ('Nancy Meyers',
'Cindy Lo', 'Jerry Martin');
Adapted from DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall
WHERE with “BETWEEN”
SELECT
FROM
WHERE
*
ORDERS
ExtendedPrice
BETWEEN 100 AND 200;
Adapted from DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall
WHERE with “LIKE”
SELECT *
FROM
SALES_DATA
WHERE Buyer LIKE 'Pete*';
Adapted from DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall
WHERE with “LIKE”
SELECT *
FROM
SALES_DATA
WHERE SKU_Description
LIKE ‘*Tent*';
Adapted from DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall
Time for Hands-On
Photo © Charles Darwin University 2005
SQL Built-in Functions
 There
are five SQL Built-in Functions:
– COUNT
– SUM
– AVG
– MIN
– MAX
Adapted from DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall
SQL Built-in Functions
SELECT SUM (ExtendedPrice)
AS Order3000Sum
FROM
ORDERS
WHERE OrderNumber = 3000;
Column
Heading
Adapted from DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall
SQL Built-in Functions (Continued)
SELECT
FROM
SUM (ExtendedPrice)
AS OrderItemSum,
AVG (ExtendedPrice)
AS OrderItemAvg,
MIN (ExtendedPrice)
AS OrderItemMin,
MAX (ExtendedPrice)
AS OrderItemMax
ORDERS;
Adapted from DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall
SQL Built-in Functions (Continued)
SELECT COUNT(*) AS NumRows
FROM
ORDERS;
Adapted from DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall
Arithmetic in SELECT Statements
SELECT Quantity * Price AS EP,
ExtendedPrice
FROM
ORDERS;
Adapted from DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall
Time for Hands-On
Photo © Charles Darwin University 2005
Retrieving Data from
More Than One Table
Join
Make a list of students including phone number
and address
Person
Phone
Address
Joining together tables
Phone
Person
PhoneID
PersonID
PhoneNum
100
1
5555532
200
1
1
5553211
400
2
5553421
600
3
3
Name
AddressID
1
Joe
10
2
Jane
20
3
Chris
30
5552234
300
500
PersonID
Address
AddressID
Company Street
Zip
10
ABC
12 Road
12345
20
XYZ
45 Road
14454
30
PDQ
78 Road
14423
5552341
5556655
The SELECT with a JOIN Clause
SELECT TABLE1.Column,
TABLE2.Column
FROM
TABLE1, TABLE2
WHERE TABLE1.PrimaryKey =
TABLE2.PrimaryKey;
Adapted from DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall
The SELECT with a JOIN Clause
SELECT PERSON.Name,
PHONE.PhoneNum
FROM
PERSON, PHONE
WHERE PERSON.PersonID =
PHONE.PersonID;
Adapted from DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall
The SELECT with two JOIN Clauses
SELECT PERSON.Name,
PHONE.PhoneNum,
ADDRESS.Zip
FROM
PERSON, PHONE, ADDRESS
WHERE PERSON.PersonID =
PHONE.PersonID
AND
PERSON.AddressID =
ADDRESS.AddressID
Adapted from DAVID M. KROENKE’S DATABASE PROCESSING, 10th Edition © 2006 Pearson Prentice Hall
The SELECT with a JOIN Clause
SELECT P.Name, PH.PhoneNum
FROM
PERSON P , PHONE PH
WHERE P.PersonID =
PH.PersonID
Alias (Shorthand)
for Table Name
Time for Hands-On
Photo © Charles Darwin University 2005
Writing SQL in
MS Access 2007
Click
“Create”
Click “Query
Design”
Click
“Close”
Click “SQL”
Click
“! Run”