偶然看到php的链式操作写法，觉得很有意思，特别记录一下 ，摘抄自网友实例

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1. 代码参考

    class sql{
        private $sql=array("from"=>"",
            "where"=>"",
            "order"=>"",
            "limit"=>"");
   
        public function from($tableName) {
            $this->sql["from"]="FROM ".$tableName;
            return $this;
        }
   
        public function where($_where='1=1') {
            $this->sql["where"]="WHERE ".$_where;
            return $this;
          }
   
        public function order($_order='id DESC') {
            $this->sql["order"]="ORDER BY ".$_order;
            return $this;
        }
   
        public function limit($_limit='30') {
            $this->sql["limit"]="LIMIT 0,".$_limit;
            return $this;
        }
        public function select($_select='*') {
            return "SELECT ".$_select." ".(implode(" ",$this->sql));
        }
    }
   
    $sql =new sql();
   
    echo $sql->from("testTable")->where("id=1")->order("id DESC")->limit(10)->select();
    //输出 SELECT * FROM testTable WHERE id=1 ORDER BY id DESC LIMIT 0,10