Backend Development
PHP Tutorial
Detailed explanation of PHP operation mysql function, mysql and php interactive function_PHP tutorial
Detailed explanation of PHP operation mysql function, mysql and php interactive function_PHP tutorial
1. Establish and close connections
1) mysql_connect()
resource mysql_connect([string hostname [:port][:/path/to/socket][,string username] [,string password]])
All parameters are optional
Example:
@mysql_connect(“localhost”, “user”, “password”)
or die(“Could not connect to mysql server !");
Note that the @ symbol means that any error message caused by a failed attempt is prohibited. What the user will see is the error message specified in die().
Note that when connecting to multiple mysql, The link ID of each connection must be specified, as follows:
$link1 = @mysql_connect(“server1″, “user”, “password”)
or die(“Could not connect to mysql server!”);
$link2 = @mysql_connect(“server2″, “user”, “password”)
or die(“Could not connect to mysql server!”);
2) mysql_pconnect()
resource mysql_pconnect ([string hostname [:port][:/path/to/socket][,string username] [,string password]])
The difference from mysql_connect() is: it will first search for the existing link, if it does not exist
Note that there is no need to explicitly close the connection (mysql_close()), because the connection will be placed in the pool, so it is called a persistent connection.
3) mysql_close()
boolean mysql_close([resource link_id] )
Closing the connection is not necessary because it can be handled by MySQL's garbage collection.
If link_id is not specified, the most recent link is closed.
2. Select the database
mysql_select_db()
boolean mysql_select_db(string db_name [, resource link_id])
3. Query MySql
1) mysql_query()
resource mysql_query(string query [, resource link_id ])
Responsible for executing query.
2) mysql_db_query()
resource mysql_db_query(string database, string query [, resource link_id])
Equivalent to mysql_select_db() + mysql_query(), from the parameters You can clearly see it in.
4. Obtain and display data
1) mysql_result()
mixed mysql_result(resource result_set, int row [,mixed field])
Get the data of a field from the specified row of result_set. Simple but inefficient.
Example:
$link1 = @mysql_connect(“server1″, “webuser”, “password”)
or die(“Could not connect to mysql server!”);
@mysql_select_db(“company”) or die(“Could not select database!”);
$query = “select id, name from product order by name”;
$result = mysql_query($query);
$id = mysql_result( $result, 0, “id”);
$name = mysql_result($result, 0, “name”);
mysql_close();
Note that the above code is just output The field value of the first piece of data in the result set, if you want to output all records, needs to be processed in a loop.
…
for ($i = 0; $i <= mysql_num_rows($result); $i++)
{
$id = mysql_result($result, 0, “id”);
$name = mysql_result($result, 0, “name”);
echo “Product: $name ($id)”;
}
…
Note that if the query field name is an alias, the alias will be used in mysql_result.
2) mysql_fetch_row()
array mysql_fetch_row(resource result_set)
Get the entire row from result_set and put the data into the array.
Example (pay attention to the clever combination with list):
…
$ query = “select id, name from product order by name”;
$result = mysql_query($query);
while(list($id, $name) = mysql_fetch_row($result)) {
echo “Product: $name ($id)”;
}
…
3) mysql_fetch_array()
array mysql_fetch_array(resource result_set [,int result_type])
An enhanced version of mysql_fetch_row().
Get each row of result_set as an associative array or/and a numerical index array.
Get two arrays by default, result_type can be set:
MYSQL_ASSOC: Returns an associative array, Field name => Field value
MYSQL_NUM: Returns a numerical index array.
MYSQL_BOTH: Gets two arrays. Therefore, each field can be referenced by index offset or by field name.
Example:
…
$query = “select id, name from product order by name” ;
$result = mysql_query($query);
while($row = mysql_fetch_array($result, MYSQL_BOTH)) {
$name = $row['name'];//or $name = $row[1];
$name = $row['id'];//or $name = $row[0];
echo “Product: $name ($id)”;
}
…
4) mysql_fetch_assoc()
array mysql_fetch_assoc(resource result_set)
Equivalent to mysql_fetch_array($result, MYSQL_ASSOC)
5) mysql_fetch_object()
object mysql_fetch_object(resource result_set)
and mysql_fetch_array() has the same function, but it returns an object instead of an array.
Example:
…
$query = “select id, name from product order by name”;
$result = mysql_query($query);
while($row = mysql_fetch_object($result)) {
$name = $row->name;
$name = $row->id;
echo “Product: $name ($id)”;
}
…
5. Selected records and affected records
1) mysql_num_rows()
int mysql_num_rows(resource result_set)
Return the rows in result_set Number.
Note that mysql_num_rows() is only effective in determining the number of records obtained by the select statement query. If you want to obtain the number of records affected by the insert/updata/delete query, you need to use mysql_affected_rows().
2) mysql_affected_rows()
int mysql_affected_rows([resource link_id])
Get the number of records affected by the insert/updata/delete query
Note that no parameters are required and the most recent result of the most recently established database connection is used by default. You can use optional Parameter link_id to select the database connection.
6. Get database and table information
1) mysql_list_dbs()
resource mysql_list_dbs([resource link_id])
Get all the information on the server Database name.
Example:
mysql_connect(“localhost”, “name”, "pwd");
$dbs = mysql_list_dbs();
while (list($db) = mysql_fetch_row(dbs)) {
echo "$db
";
}
Note that the output results are related to the user permissions used.
2) mysql_db_name()
string mysql_db_name(resource result_set, interger index)
Get the result_set returned in mysql_list_dbs() The database name with the center position as index.
3) mysql_list_tables()
resource mysql_list_tables(string database [,resource link_id])
Get all table names in the database.
4) mysql_tablename()
string mysql_tablename(resource result_set, interger index)
Get the table name at index in the result_set returned by mysql_list_tables().
While learning PHP’s COM and .Net (Windows) functions, I discovered a I found the example of operating SQL SERVER through COM and found relevant information, so I came up with this article about connecting ACCESS with PHP. I believe there are already many on the Internet, so I’ll post it here.
My machine environment: WIN2000, APACHE2, PHP Version 5.1.0RC1
< ;?php
$conn = new COM(“ADODB.Connection”) or die(“Cannot start ADODB.Connection”);
$conn->Open(“Provider=Microsoft.Jet.OLEDB.4.0 ;Data Source=D:\php5\netBook.mdb”);
$rs = $conn->Execute(“select * from manage”); // Recordset
$num_columns = $rs-> ;Fields->Count();
echo $num_columns . “
n”;
for ($i=0; $i < $num_columns; $i++) {
$fld[$i] = $rs->Fields($i);
}
$rowcount = 0;
while (!$rs->EOF) {
for ($ i=0; $i < $num_columns; $i++)
{
echo htmlspecialchars($fld[$i]->value) . “t”;
}
echo “< ;br />n”;
$rowcount++; // rowcount increments
$rs->MoveNext();
}
$rs->Close(); //Close Dataset
$conn->Close();
?>
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
Video Face Swap
Swap faces in any video effortlessly with our completely free AI face swap tool!
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
PHP and Python: Comparing Two Popular Programming Languages
Apr 14, 2025 am 12:13 AM
PHP and Python each have their own advantages, and choose according to project requirements. 1.PHP is suitable for web development, especially for rapid development and maintenance of websites. 2. Python is suitable for data science, machine learning and artificial intelligence, with concise syntax and suitable for beginners.
PHP in Action: Real-World Examples and Applications
Apr 14, 2025 am 12:19 AM
PHP is widely used in e-commerce, content management systems and API development. 1) E-commerce: used for shopping cart function and payment processing. 2) Content management system: used for dynamic content generation and user management. 3) API development: used for RESTful API development and API security. Through performance optimization and best practices, the efficiency and maintainability of PHP applications are improved.
PHP's Purpose: Building Dynamic Websites
Apr 15, 2025 am 12:18 AM
PHP is used to build dynamic websites, and its core functions include: 1. Generate dynamic content and generate web pages in real time by connecting with the database; 2. Process user interaction and form submissions, verify inputs and respond to operations; 3. Manage sessions and user authentication to provide a personalized experience; 4. Optimize performance and follow best practices to improve website efficiency and security.
The Enduring Relevance of PHP: Is It Still Alive?
Apr 14, 2025 am 12:12 AM
PHP is still dynamic and still occupies an important position in the field of modern programming. 1) PHP's simplicity and powerful community support make it widely used in web development; 2) Its flexibility and stability make it outstanding in handling web forms, database operations and file processing; 3) PHP is constantly evolving and optimizing, suitable for beginners and experienced developers.
PHP and Python: Different Paradigms Explained
Apr 18, 2025 am 12:26 AM
PHP is mainly procedural programming, but also supports object-oriented programming (OOP); Python supports a variety of paradigms, including OOP, functional and procedural programming. PHP is suitable for web development, and Python is suitable for a variety of applications such as data analysis and machine learning.
PHP and Python: Code Examples and Comparison
Apr 15, 2025 am 12:07 AM
PHP and Python have their own advantages and disadvantages, and the choice depends on project needs and personal preferences. 1.PHP is suitable for rapid development and maintenance of large-scale web applications. 2. Python dominates the field of data science and machine learning.
Why Use PHP? Advantages and Benefits Explained
Apr 16, 2025 am 12:16 AM
The core benefits of PHP include ease of learning, strong web development support, rich libraries and frameworks, high performance and scalability, cross-platform compatibility, and cost-effectiveness. 1) Easy to learn and use, suitable for beginners; 2) Good integration with web servers and supports multiple databases; 3) Have powerful frameworks such as Laravel; 4) High performance can be achieved through optimization; 5) Support multiple operating systems; 6) Open source to reduce development costs.
PHP: Handling Databases and Server-Side Logic
Apr 15, 2025 am 12:15 AM
PHP uses MySQLi and PDO extensions to interact in database operations and server-side logic processing, and processes server-side logic through functions such as session management. 1) Use MySQLi or PDO to connect to the database and execute SQL queries. 2) Handle HTTP requests and user status through session management and other functions. 3) Use transactions to ensure the atomicity of database operations. 4) Prevent SQL injection, use exception handling and closing connections for debugging. 5) Optimize performance through indexing and cache, write highly readable code and perform error handling.
