A simple web example combining PHP and database Code Analysis (PHP Beginner)_PHP Tutorial

However, apart from the installation part, which has more or less Windows-specific instructions, the rest are the same for all platforms. By the way, for the installation part, please see the installation guide on this site. In this tutorial, we will build a small website step by step, using the following features of PHP and MySQL:
　1. View the database;
　2. Edit the records of the database;
　3. Modify the database records;
　4. Delete the records of the database.
We will learn MySQL and PHP at the same time and feel them together. This article can be learned directly from here. If you don’t know how to install and configure Apache+PHP+Mysql, please check out the related articles on the web teaching network!
First run the web server (PHP extension has been added); run MySQL.
Create and manipulate a MySQL database:
First we need to create the database and tables to be used. The database is named "example", the table is named "tbl", and has the following fields: identification number, first name, last name and information. To complete the database creation and table definition work through the mysql terminal, just double-click or run c:mysqlbinmysql.exe.
If you want to see which tables have been defined in MySQL, you can use (note that mysql> is the terminal prompt):
Mysql> show databases;
This command may display the following information :
　+----------+
　| Database |
　+----------+
　| mysql |
　| test |
+----------+
2 rows in set (0.01 sec)
To define a new database (example), type:
Mysql> create database example; < ; Enter>
You will see a response, such as:
Query OK, 1 row affected (0.17 sec) That’s right, we now have a new database. Now we can create a new table in the library, but first we need to select the new database:
Mysql> use example;
The answer should be:
Database changed
Now we can create a table with the following fields:
Index number - integer
User name - a string with a maximum length of 30
User last name - a string with a maximum length of 50
Free information - A string with a maximum length of 100
Type the following command at the MySQL prompt to create the table:
MySQL> create table tbl (idx integer(3), UserName varchar(30), LastName varchar(50), FreeText varchar(100));
The answer should be:
Query OK, 0 rows affected (0.01 sec)
Okay, let’s take a look at the table from the MySQL prompt. What does it look like? Type the command:
MySQL> show columns from tbl;
We will get the following results:
+-----------+-- ------------+------+-----+---------+-------+
　 | Field | Type | Null | Key | Default | Extra |
　+----------+---------------+------+--- --+---------+-------+
　| idx | int(3) | YES | | NULL | |
　| UserName | varchar(30) | YES | | NULL | |
| LastName | varchar(50) | YES | | NULL | |
| FreeText | varchar(100) | YES | | NULL | |
　+------ ---+--------------+------+-----+---------+-------+

　4 rows in set (0.00 sec)
　Here, we can see the contents of the table "tbl" we just created.
Now let’s take a look at what’s in the table. Type the following command:
MySQL> select * from tbl;
This command is used to display all data in table "tbl". The output might be:
Empty set (0.07 sec) The reason why we get this result is because we haven’t inserted any data into the table yet. Let's insert some data into the table and type:
MySQL> insert into tbl values ​​(1,'Rafi','Ton','Just a test');
Query OK, 1 row affected (0.04 sec)
As you can see above, the values ​​we insert into the table are in the order in which we defined the table earlier, because the default order is used. We can set the order of data, the syntax is as follows:
　MySQL> insert into tbl (idx,UserName,LastName,FreeText) values ​​(1,'Rafi','Ton','Just a test');
OK, now we can look at the contents of the table again:
MySQL> select * from tbl;
This time the result is:
+-- ----+----------+----------+-------------+
| idx | UserName | LastName | FreeText |
　+------+----------+----------+-------------+
| 1 | Rafi | Ton | Just a test |
+------+----------+----------+--- ----------+
　1 row in set (0.00 sec)
　 Now we can see the structure of the table and the content of each cell.
Now we want to delete the data. To achieve this we should type:
　MySQL> delete from tbl where idx=1 limit 1; Query OK, 1 row affected (0.00 sec)
　Okay, give some explanation.We are telling MySQL to delete records from the "tbl" table, delete those records with an idx field value of 1, and limit deletion to only one record. If we don't limit the number of deleted records to 1, then all records with idx 1 will be deleted (in this example we only have one record, but nonetheless, I just wanted to make this more clear).
Unfortunately, we get an empty table again, so let's enter it again:
MySQL> insert into tbl values ​​(1,'Rafi','Ton','Just a test');
Query OK, 1 row affected (0.04 sec)
Another thing you can do is to modify the content of the specified field and use the "update" command:
MySQL>update tbl set UserName='Berber' where UserName='Rafi';
　Query OK, 1 row affected (0.01 sec)
　Rows matched: 1 Changed: 1 Warnings: 0
　This command Will search for all records with UserName "Rafi" and change it to "Berber". Note that the set part and where part do not have to be the same. We can search one field but change another field. Moreover, we can perform searches with two or more criteria.
　MySQL>update tbl set UserName='Rafi' where UserName='Berber' and LastName='Ton';
　Query OK, 1 row affected (0.04 sec)
　This query Searched two fields and changed the value of UserName


Combining PHP and MySQL
In this part, we will build a single PHP-based web site to control the previous Create a MySQL table.
We will build the following site structure (assuming you already know some basic HTML knowledge):
1. index.php3 is used to view the table on the front end 2. add.php3 is used to insert data into the table
　3. Modify.php3 is used to modify the records in the table 4. del.php3 is used to delete the records in the table
First, we want to check the database and take a look at the following script:
　----- -------------------------------------------------- -----------------------
　Index.php

　
　Web Database Sample Index
　
　
　

Data from tbl

　
mysql_connect() or die ("Problem connecting to DataBase");
$query = "select * from tbl";
$result = mysql_db_query("example", $query);
if ( $result) {
echo "Found these entries in the database:

";
echo "
　
　
　
　
　";
　while ($ r = mysql_fetch_array($result))
　{
$idx = $r["idx"];
$user = $r["UserName"];
$last = $r[" LastName"];
$text = $r["FreeText"];
echo "
/td>
　
　
　";
　}
　echo "";
　}
else
　{
echo "No data.";
　}
mysql_free_result($result);
include ('links.x' );
　?>
　
　
------------------------ -------------------------------------------------- -------
Okay, here are some instructions:
We first create a thml document using normal html tags. When we want to transfer from html to PHP, we use to open the PHP part. This tells the web server to treat the following text as PHP syntax instead of ordinary html. Use ?> to end the PHP part.
The mysql_connect() command tells PHP to establish a connection to the MySQL server. If the connection is established successfully, the script will continue. If not, the die command information "Problem connecting to Database" will be printed out (if you want to see more information about mysql_connect and other PHP functions, you can go to http://www Find it in the documentation under .php.net).
Now, if MySQL is installed as we discussed above, that is enough.But if you are using the pre-installed MySQL (like an ISP), you should use the following command:
mysql_connect (localhost, username, password);
We can set $query to what we want to execute in MySQL query, and then use the mysql_db_query command to execute it:
$result = mysql_db_query("example", $query);
At this time, "example" represents the name of the database and $query is the query to be performed.
We use the MySQL command select (as described above) to get all the data from the table:
$query = "select * from tbl";
Briefly explain the role of $result, if If executed successfully, the function will return a MySQL result identifier of the query result, or false if an error occurs. What is returned is not a result but an identifier, which can be converted later into the information we need.
Now, we want to check whether there is a record in the database, and if so, print the result according to the html table structure. To check if the data exists, we use the if command with the following syntax:
if (argument) {
"do something;"
} else {
"do something different;"
}
At this time, "do something" is the command you want to execute when argument=true, and "do something different" is the command you want to execute when argument=false.
Note that we use the echo command to output some html tags to establish the html table structure. Only text output from PHP commands will be treated as HTML content - PHP commands themselves will not be treated as HTML content. Another command we use is the while instruction, with the following format:
while (argument)) {
"something to do";
}
The while loop will continue when argument=true Repeat, executing the set of instructions in {}.
Here we combine the while loop and the PHP function $r=mysql_fetch_array($result). This function retrieves a record based on the corresponding result identifier and places the result in an associative array $r, using the field name as the array key. In our script, we will get an array: $r['idx'], $r['UserName'], $r['LastName'] and
　$r['FreeText'].
We can also use the mysql_fetch_row function, which will put the results in an ordered array. We can use $r[0], $r[1], $r[2] and $r[3] to Get the corresponding value. .
Now that we have all the information, we can print it out in an html table:
The following is the quoted content:
echo "

　
　
;";
Now we can release the MySQL connection and release some resources by using the mysql_free_result($result) function.
Another useful feature of PHP is the ability to include text files in scripts. Let us assume that you have some reusable code (such as links to other pages), we can use the include function, which can save some code and time. Moreover, if we want to change this code, we only need to change the content of the included file, and it will take effect in all files that include it.
Here we create a text file called Links.x, which will store all the link menus we want to use on each page.
　

　

　
• Home
  　
• Add a new entry to the DataBase
  　
• Edit an entry
  　
• Delete an entry from the DataBase
  　

　The syntax of include is:
　Include (' included_text_file');
Now we can use ?> to close the PHP part, and use

User Name	Last Name	Domain Name	Request Date
$last	$text
$idx< ;/td>	$user	$last	$text