PHP operation MySQL and encapsulation common functions use outer joins to connect 3 tables case

<?php
Header ("Content-type;text/html;charset=utf-8");

Database connection
Define (' db_host ', ' localhost ');
Define (' Db_user ', ' root ');
Define (' Db_password ', ' admin ');
Define (' db_name ', ' php2016 ');
Connect to MySQL server
function _connect () {
Global represents the meaning of the globals, with the intention of accessing the variable outside of the function
Global $_conn;
if (!$_conn=mysql_connect (Db_host,db_user,db_password)) {
Echo ' failed to connect to MySQL server ';
Echo ' Error number: ', Mysql_errno (), ' <br/> ';
Echo ' Error message: ', mysql_error (), ' <br/> ';
}
}

Connect to the specified database
function _select_db () {
if (!mysql_select_db (db_name)) {
Echo ' cannot find the specified database ';
Echo ' Error number: ', Mysql_errno (), ' <br/> ';
Echo ' Error message: ', mysql_error (), ' <br/> ';
}
}

Set character sets
function _set_names () {
if (!mysql_query (' SET NAMES UTF8 ')) {
Echo ' character set failed ';
Echo ' Error number: ', Mysql_errno (), ' <br/> ';
Echo ' Error message: ', mysql_error (), ' <br/> ';
}
}

Executes the SQL statement, returning a result set $_sql means an SQL statement
function _query ($_sql) {
if (!$_result=mysql_query ($_sql)) {
Exit (' SQL execution failed ');
}
return $_result;
}

_query ($_sql) is the result set
/*
* _fetch_array only one data set for the specified data set
*/
function _fetch_array ($_sql) {
Return Mysql_fetch_array (_query ($_sql), MYSQL_ASSOC);
}
/*
* _fetch_array_list can return all data for a specified dataset
*/
function _fetch_array_list ($_result) {
return mysql_fetch_array ($_RESULT,MYSQL_ASSOC);
}

/*
* The _html () function denotes HTML filtering of strings, as arrays, displayed as arrays, as strings, as strings
*/

function _html ($_string) {
if (Is_array ($_string)) {
foreach ($_string as $_key =>$_value) {
$_string[$_key]=htmlspecialchars ($_value);
}
}else {
$_string=htmlspecialchars ($_string);
}
return $_string;
}
Initializing the database
_connect (); Connect to MySQL server
_select_db (); Connect to the specified database
_set_names (); Set character sets

$sql = "Select Goods.id,goods.name as goods_name,colors.name as colors_name,size.name as size_name from goods left JOIN CO Lors on goods.id=colors.id left join size on goods.id=size.id; ";
$res =_query ($sql);
$_html=array ();
while (!! $_rows=_fetch_array_list ($res)) {
$_html[' id ']=$_rows[' id '];
$_html[' goods_name ']=$_rows[' goods_name '];
$_html[' colors_name ']=$_rows[' colors_name '];
$_html[' size_name ']=$_rows[' size_name '];
$_html=_html ($_html);

echo $_html[' id '];echo $_html[' goods_name ']; echo $_html[' colors_name '];echo $_html[' size_name ']. ' <br/> ';
}
?>

PHP operation MySQL and encapsulation common functions use outer joins to connect 3 tables of cases