Articles Databases
Databases
PHPLib and Multiple Databases - Page 3
by: Peter Moulding
|
November 7, 2000
Expanding PHPLIB
PHPLIB accesses databases through an object created from class DB_Sql.
Db_mysql.inc includes the DB_Sql class as modified for MySQL. We will
extend DB_Sql by adding code to common.php3, after the line that includes
db_mysql.inc.
DB_Sql contains many functions to perform queries. The one we want to
change is:
<?php
/* public: connection management */
function connect($Database = "", $Host = "", $User = "", $Password = "") {
/* Handle defaults */
if ("" == $Database)
$Database = $this->Database;
if ("" == $Host)
$Host = $this->Host;
if ("" == $User)
$User = $this->User;
if ("" == $Password)
$Password = $this->Password;
/* establish connection, select database */
if ( 0 == $this->Link_ID ) {
$this->Link_ID=mysql_pconnect($Host, $User, $Password);
if (!$this->Link_ID) {
$this->halt("pconnect($Host, $User, \$Password) failed.");
return 0;
}
if (!@mysql_select_db($Database,$this->Link_ID)) {
$this->halt("cannot use database ".$this->Database);
return 0;
}
}
return $this->Link_ID;
}
?>
Find the connect() function in your db_mysql.inc (or the .inc for your
database), then copy it in to common.php3 somewhere after the include of
db_mysql.inc. You will have to wrap it in a class definition as described
at the end of this article.
I find the code hard to read. Therefore, the first thing to do is make the copied code
readable:
<?php
/* public: connection management */
function connect($Database = "", $Host = "", $User = "", $Password = "") {
/* Handle defaults */
if ("" == $Database) {
$Database = $this->Database;
}
if ("" == $Host) {
$Host = $this->Host;
}
if ("" == $User) {
$User = $this->User;
}
if ("" == $Password) {
$Password = $this->Password;
}
/* establish connection, select database */
if ( 0 == $this->Link_ID ) {
$this->Link_ID=mysql_pconnect($Host, $User, $Password);
if (!$this->Link_ID) {
$this->halt("pconnect($Host, $User, \$Password) failed.");
return 0;
}
if (!@mysql_select_db($Database,$this->Link_ID)) {
$this->halt("cannot use database ".$this->Database);
return 0;
}
}
return $this->Link_ID;
}
?>
I indented the code so the levels let me match the brackets, with the
enclosed code. This avoids errors caused by missing brackets. I added
brackets to single lines. PHP lets you get away without brackets around
single lines of code after if statements. As soon as you add extra code,
the shortcut fails. I suggest always use the brackets to avoid errors when
you add code later.
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