案例：封装一个MySQLi操作类
<?php
# 组装查询语句
$add_time = time();
$ret = select($db,'user','country="日本"','uid DESC','0,5');
# 组装插入语句
$add_time = time();
$sql = "INSERT INTO `director` ( name,phone,country,add_time) VALUES ( '一本道','18844441111','日本','{$add_time}');";
$ret = insert($db,$sql);
# 组装修改语句
$sql = "UPDATE `director` SET name='长江',phone='15500001111' WHERE tid=3;";
$ret = save($db,$sql);
# 组装删除语句
$sql = "DELETE FROM `director` WHERE tid=5;";
$ret = delete($db,$sql);
# 连接方法
function connect($db){
# 连接数据库
$conn = @mysqli_connect($db['host'],$db['user'],$db['pass'],$db['name'],'3306');
if(!$conn){
# 连接错误，抛出异常
exit('数据库报错: '.mysqli_connect_error());
}
return $conn;
}
# 统计数量
function count_number($db,$table,$where){
$sql = "SELECT COUNT(*) AS count_number FROM ".$table." WHERE ".$where;
$return = mysqli_query($db,$sql);
$return = mysqli_fetch_assoc($return);
# 关闭数据库
mysqli_close($db);
return $return['count_number'];
}
# 查询单个数据
function find_one($db,$table,$filed,$where){
$sql = "SELECT ".$filed." FROM ".$table.' WHERE '.$where.' LIMIT 1';
$return = mysqli_query($db,$sql);
$return = mysqli_fetch_assoc($return);
# 关闭数据库
mysqli_close($db);
return $return;
}
# 查询单条数据
function find($db,$table,$where,$order){
$sql = "SELECT * FROM ".$table.' WHERE '.$where;
if($order){
$sql .= ' ORDER BY '.$order;
}
$sql .= 'LIMIT 1';
$return = mysqli_query($db,$sql);
$return = mysqli_fetch_assoc($return);
# 关闭数据库
mysqli_close($db);
return $return;
}
# 查询方法
function select($db,$table,$where,$order,$limit){
$sql = "SELECT * FROM ".$table.' WHERE '.$where;
if($order){
$sql .= 'ORDER BY '.$order;
}
if($limit){
$sql .= ' LIMIT '.$limit;
}
$return = mysqli_query($db,$sql);
if($return){
while ( $row = mysqli_fetch_assoc($return)) {
$rows[] = $row;
}
mysqli_free_result($return);
}
# 关闭数据库
mysqli_close($db);
return $rows;
}
# 插入方法
function insert($db,$sql){
# 执行插入
$return = mysqli_query($db,$sql);
if($return){
$return = mysqli_insert_id($db);
}
# 关闭数据库
mysqli_close($db);
return $return;
}
# 修改方法
function save($db,$sql){
$return = mysqli_query($db,$sql);
# 关闭数据库
mysqli_close($db);
return $return;
}
# 删除方法
function delete($db,$sql){
$return = mysqli_query($db.$sql);
# 关闭数据库
mysqli_close($db);
return $return;
}
?>