MySQL hinzufügen, löschen, ändern, abfragen – CURD-Operation

<?php
$conn=mysql_connect("localhost","root","root");
mysql_query("set names utf8");
mysql_select_db("test");
/**
**insert 操作
*/
function insert($table,$data){
	if(!is_array($data))return false;
	$sql_key="";
	$sql_values="";
	foreach($data as $key=>$val){
			$sql_key.=$key.",";
			$sql_values.="&#39;".$val."&#39;".",";
	}
	$news_key=trim($sql_key,",");
	$news_values=trim($sql_values,",");
	$sql="INSERT INTO `{$table}` ({$news_key}) VALUES ({$news_values})";
	$re=query($sql);//执行sql语句
	if($re){
		return mysql_insert_id();//返回最后一次执行的id号
	}else{
		return false;
	}
}
//查询
function select($tableName,$field="*",$where="",$order="",$limit="",$group="",$having=""){
		$sql="select $field from $tableName $where $group $having $order $limit";
		$re=query($sql);
		
		if(is_resource($re)){
			$arr=array();
			while($result=mysql_fetch_assoc($re)){
				$arr[]=$result;
				
			}
			return $arr;
		}else{
			return false;
		}
}
//删除
 function delete($tableName,$where=""){
		$sql="delete from $tableName $where";
		$re=query($sql);
		if($re){
			return mysql_affected_rows ();
		}else{
			return false;
		}
		
	}
	//修改
 function update($tableName,$array,$where=""){
		$fvList="";
		foreach ($array as $k=>$v) {
			$fvList.=",".$k."=&#39;".$v."&#39;";
		}
			$fvList=substr($fvList,1);
			$sql="update $tableName set $fvList $where";
			echo $sql;
			$re=query($sql);
			if($re){
				return mysql_affected_rows();
			}else{
				return false;
		}
	}
function query($sql){
	if(!$sql)return false;
	return mysql_query($sql);
}
var_dump(delete(&#39;users&#39;,&#39;where id=1&#39;));
?>