PHP accesses MYSQL database encapsulation class (with function description)_PHP tutorial

/*
MYSQL database access encapsulation class
MYSQL Data access method, php4 supports the process access method starting with mysql_, php5 starts to support the process starting with mysqli_ and the mysqli object-oriented
access method. This encapsulation class uses mysql_ to encapsulate the general process of
data access:
1, connect to the database mysql_connect or mysql_pconnect
2, select the database mysql_select_db
3, execute the SQL query mysql_query
4, process the returned data mysql_fetch_array mysql_num_rows mysql_fetch_assoc mysql_fetch_row etc
*/
class db_mysql
{
var $querynum = 0; //The number of times the current page process queries the database
var $dblink; //Database connection resources
//Link database
function connect($dbhost ,$dbuser,$dbpw,$dbname='',$dbcharset='utf-8',$pconnect=0 , $halt=true)
{
$func = empty($pconnect) ? 'mysql_connect ' : 'mysql_pconnect' ;
$this->dblink = @$func($dbhost,$dbuser,$dbpw) ;
if ($halt && !$this->dblink)
{
$this->halt("Unable to connect to database!");
}
//Set query character set
mysql_query("SET character_set_connection={$dbcharset},character_set_results={$dbcharset },character_set_client=binary",$this->dblink) ;
//Select database
$dbname && @mysql_select_db($dbname,$this->dblink) ;
}
/ /Select database
function select_db($dbname)
{
return mysql_select_db($dbname,$this->dblink);
}
//Execute SQL query
function query ($sql)
{
$this->querynum++ ;
return mysql_query($sql,$this->dblink) ;
}
//Return the latest connection handle The number of record rows affected by the associated INSERT, UPDATE or DELETE query
function affected_rows()
{
return mysql_affected_rows($this->dblink);
}
//Get the result The number of concentrated rows is only valid for the result set of select query
function num_rows($result)
{
return mysql_num_rows($result) ;
}
//Get a single-cell query Result
function result($result,$row=0)
{
return mysql_result($result,$row);
}
//Get the ID generated by the previous INSERT operation, Only valid for operations with AUTO_INCREMENT ID on the table
function insert_id()
{
return ($id = mysql_insert_id($this->dblink)) >= 0 ? $id : $this-> ;result($this->query("SELECT last_insert_id()"), 0);
}
//Extract the current row from the result set and return it in the form of an associative array represented by a number as the key
function fetch_row($result)
{
return mysql_fetch_row($result) ;
}
//Extract the current row from the result set and return it in the form of an associative array represented by the field name key
function fetch_assoc($result)
{
return mysql_fetch_assoc($result);
}
//Extract the current row from the result set and return it in the form of an associative array represented by the field name and number as key
function fetch_array($result)
{
return mysql_fetch_array($result);
}
//Close the link
function close()
{
return mysql_close($ this->dblink) ;
}
//Output a simple error html prompt message and terminate the program
function halt($msg)
{
$message = " nn" ;
$message .= "n" ;
$message .= " n" ;
$message .= "n" ;
$message .= "Database error: ".htmlspecialchars($msg)."n" ;
$message .= "$message .= "" ;
echo $message ;
exit ;
}
}
?>