Copyright © 2003 Pearson Education, Inc. Slide 8-1 The Web Wizard’s Guide to PHP by David Lash
Dec 27, 2015
Copyright © 2003 Pearson Education, Inc. Slide 8-2
CHAPTER 8Using Databases with PHP
Scripts:Using MySQL Database with PHP
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Objectives To understand the advantages of using databases
to store Web data To learn how to prepare a MySQL database for use
with PHP To learn how to store, retrieve, and update data in
a MySQL database
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What is a database?
A set of data organized into one or more computer files.
Using files for product inventory is a type of database
Generally the term is reserved for more formal database systems like access, Oracle or MySQL.
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Advantages of Databases Over Files
Faster access Better concurrent access Easier changes to data and scripts Increased security
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Relational Database? Relational databases store data in tables (usually
more than one) with defined relationships between the tables.
Product Number
Product Cost Weight Number Avail
0 Hammer $5.00 12 123
1 Screw Driver $3.00 2 144
2 Wrench $2.50 1.5 244
Primary key
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Which Database System
PHP works with a variety of databases that include: Oracle Access Ingres SQL Server MySQL
We will be using MySQL since its simple to use, free and very popular.
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Using A Query Language When using a database, we use a separate
query language called the Structured Query Language (SQL).
PHPScript
MySQLDatabase
SendSQL Query
QueryResults
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Creating a Database Instance
Once you have access to a server with MySQL installed, you need a database instance created for you (which I have done). Usually created by a database administrator Creates a database instance, userid and
password.
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Creating Your Database Tables
Once the database instance is created you need to create your tables. Use SQL CREATE TABLE command
CREATE TABLE Products (ProductID INT,
Product_descr TEXT);
The name of the table. First table column can
hold integer data.
SQL commands are shown in upper case buteither upper or lower case can be used.
Second table column canhold character data.
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Other Data Types?
MySQL supports many other data types beyond TEXT and INT. Here are a few : TEXT specifies that the table column can hold a large
amount of character data. It can use space inefficiently since it reserves space for up to 65,535 characters.
CHAR(N) specifies a table column that holds a fixed length string of up to N characters (N must be less than 256).
VARCAR(N) specifies a table column that holds a variable length string of up to N characters and removes any unused spaces on the end of the entry.
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Other Data Types?
INT specifies a table column that holds an integer with a value from about –2 billion to about 2 billion.
INT UNSIGNED specifies a table column that holds an integer with a value from 0 to about 4 billion.
SMALLINT specifies a table column that holds an integer with a value from –32,768 to 32,767.
SMALLINT UNSIGNED specifies a table column that holds an integer with a value from 0 to 65,535.
DECIMAL(N,D) specifies a number that supports N total digits, of which D digits are to the right of the decimal point.
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Some additional CREATE TABLE Options
Can specify some additional options in CREATE TABLE:
CREATE TABLE Products (ProductID INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY, Product_desc VARCHAR(50), Cost INT, Weight INT, Numb INT);
An INT UNSIGNED meansthat ProductID must bepositive values.
ProductID must bespecified for each row.
Automatically addone to each newProductID.
Make thisthe primarykey for table.
Up to 50characterslong
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Issuing CREATE TABLE From PHP Script Segment
1. $connect = mysqli_connect($server, $user, $pass);2. if ( !$connect ) {3. die ("Cannot connect to $server using $user");4. } else {5. mysqli_select_db('MyDatabaseName');6. $SQLcmd = 'CREATE TABLE Products( ProductID INT UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY, Product_desc VARCHAR(50), Cost INT, Weight INT, Numb INT )';7. mysqli_query($SQLcmd, $connect);8. mysqli_close($connect);9. }
Issue the SQL queryto the database.
Connect to MySQL
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Script Browser OutputExecute code: http://itm325.itmbsu.net/jstudent/Examples/Ch8/table_create.php
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Inserting Data
Once the database and table are created you will need to insert data
Use the SQL INSERT command
INSERT INTO Products VALUES( '0', 'Hammer', 5, 12, 123 );
Each item goes into aseparate table column in a table row.
Table Name
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A Full Example
Consider an application that allows end-user to enter inventory data:Item Description: <input type="text" size="20"
maxlength="20" name="Item">Weight: <input type="text" size="5"
maxlength="20" name="Weight">Cost: <input type="text" size="5"
maxlength="20" name="Cost">Number Available:<input type="text" size="5"
maxlength="20" name="Quantity">
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Script Output
This script can be executed at: http://itm325.itmbsu.net/jstudent/Examples/Ch8/insert.html
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Retrieving Data
Two major ways to retrieve data: 1. Retrieving all elements from a table
2. Searching for specific records in a table
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Retrieving Data
To retrieve all data, use the following SQL command
For example1. $connect = mysqli_connect('Localhost', 'phppgm',
'mypasswd');
2. $SQLcmd = 'SELECT * FROM Products';
3. mysqli_select_db('MyDatabase');
4. $results_id = mysqli_query($SQLcmd, $connect);
SELECT * FROM TableName;
The asterisk ("*")means get all the data
The name of the table toget the data from.
SQL SELECTStatement.
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Using mysqli_fetch_row()
Use the mysqli_fetch_row() function to retrieve data one row at a time
while ( $row = mysqli_fetch_row($results_id)) {
foreach ( $row as $field ) {
print "Field=$field”;
}
}
Access each field in thetable row results.
Access each row from themysqli_query() results.
(A different row each iteration).
$results_id variable is setfrom mysqli_query()
function call.
Output each itemof the $row array.
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Script Output
This script can be executed at: http://itm325.itmbsu.net/jstudent/Examples/Ch8/query.html
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Searching For Specific Records
Use the SELECT SQL statement with a WHERE clauseSELECT * FROM TableName WHERE
(test_expression);
The asterisk (“*”) meanslook at all table columns.
Specify the table name to look at.
Specify a test expressionto evaluate
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Selected WHERE CLAUSE Test Operators
Table 8.1 Selected SQL WHERE Clause Operators
Operator
SQL Query Example Meaning
= SELECT * FROM Products WHERE (Product_desc = 'Hammer');
Retrieve those rows from the Products table that have a Product_desc column with a value equal to Hammer.
> SELECT * FROM Products WHERE (Cost > '5');
Retrieve those rows from the Products table that have a Cost column with a value greater than 5.
< SELECT * FROM Products WHERE (Numb < '3');
Retrieve those rows from the Products table that have a Numb column with a value less than 3.
<= SELECT * FROM Products WHERE (Cost <= '3');
Retrieve those rows from the Products table that have a Cost column with a value less than or equal to 3.
>= SELECT * FROM Products WHERE (Weight >= '10');
Retrieve those rows from the Products table that have a Weight column with a value greater than or equal to 10.
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Consider the following example …
The following example searches a hardware inventory database for a specific part name entered by the user.
The form uses the following key HTML form element definition.
<input type="text" name="Search" size="20">
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Would have the following output …
This script can be executed at: http://itm325.itmbsu.net/jstudent/Examples/Ch8/search.html
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Updating a Database Record
Use SQL UPDATE command when needing to update a database record:
UPDATE Table_name
SET col1=chng_express1,col2=chng_express2, . . .
WHERE test_expression
Specify the name ofthe table to update.
Specify one or more table column toreceive the results of an expression. Optionally specify a WHERE
Optionally specify a WHERE clauseand test expression.
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For Example …
The following looks through the Products table for values of Product_desc equal to Hammer.
When it finds it, it decrements the Count column value by 1.
UPDATE Products SET Count=Count-1 WHERE 'Product_desc=Hammer'
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A Full Example …
Consider the following example Displays current inventory Asks end-user to decrement value for 1 item Uses the following HTML Hammer<input type="radio“ name="Product" value="Hammer" >
Screwdriver <input type="radio“ name="Product" value="Screwdriver" >
Wrench<input type="radio" name="Product“ value="Wrench"
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Would output the following: Execute this example at
http:http://itm325.itmbsu.net/jstudent/Examples/Ch8/sale.html
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Use of the mysqli_fetch_array() function
The mysqli_fetch_array(), by default, returns an array that can be read either as a sequential array or as an associative array. You can read more about it here. Here is an example using the
mysql_fetch_array() Here is the source code.
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Summary A database is a set of data organized into one or more
computer files. Relational databases store data in tables
Before you can start to work with a MySQL database, you must install a copy of MySQL on your personal computer or Web server, create a database instance for your script and create your initial tables by issuing the SQL CREATE TABLE command.
Use the SQL SELECT statement to retrieve data from a MySQL database and include a WHERE clause to select specific table rows..