基于ci框架sql拼装

<?php
class lms_model {
    public $table = 'table_name';

    /**
     * and 条件在前 or 在后
     */
    public $where_array = array(
      array( 'part_sql' => ' time_day >=? ' , 'key' => 'time_day_start', 'op' => 'AND' , 'type' => 'where') ,
     array( 'part_sql' => ' time_day <=? ' , 'key' => 'time_day_end', 'op' => 'AND' , 'type' => 'where') ,
     array( 'part_sql' => ' group by ? ' , 'key' => 'org' , 'type' => 'group') ,
     array( 'part_sql' => ' order by ? desc ' , 'key' => 'id' , 'type' => 'order') ,
     array( 'part_sql' => ' limit ? ' , 'key' => 'limit' , 'type' => 'limit')
    );
    /**
     * 拼接sql
     */
    public function get_where($request) {

        if( empty($request) ) {
            return '';
        }

        extract($request);

        $sql = $where_sql = $group_sql = $order_sql = $limit_sql = '';

        $bind_data = array();

        //拼接where

        foreach($this->where_array as $k => $v) {
         if( isset($$v['key']) && $v['type'] == 'where') {
             $where_sql .= $v['op'] . $v['part_sql'];
             $bind_data[] = $$v['key'];
             continue;
         }

         if( isset($$v['key']) && $v['type'] == 'group') {
             $group_sql .= $v['part_sql'];
             $bind_data[] = $$v['key'];
                continue;
         }

         if( isset($$v['key']) && $v['type'] == 'order') {
             $order_sql .= $v['part_sql'];
             $bind_data[] = $$v['key'];
                continue;
         }

         if( isset($$v['key']) && $v['type'] == 'limit') {
             $limit_sql .= $v['part_sql'];
             $bind_data[] = $$v['key'];
                continue;
         }
        }


        if(!empty($where_sql)) $sql = ' where ' . ltrim($where_sql,"and");

        $sql .= $group_sql;

        $sql .= $order_sql;

        $sql .= $limit_sql;

        return array('sql' => $sql , 'bind_data' => $bind_data);
    }
    public function insert() {
    }
    public function update() {
    }
    public function delete() {
    }
    /**
     * args['field'] default *
     * args['where'] default null
     * args['group'] default null
     * args['order'] default null
     * args['limit'] default null
     */
    public function get_data($args) {
        $where = $this->get_where($args);
        $field='*';
        if( isset($args['field']) && !empty($args['field']) ) $field = $args['field'];
        $sql = " SELECT {$field} FROM {$this->table} {$where['sql']}";
        echo $sql;
        echo "
";
        print_r($where['bind_data']);
        echo "
";
    }
    /**
     * args['field'] default *
     * args['where'] default null
     * args['group'] default null
     * args['order'] default null
     */
    public function get_one($args) {
        $args['limit'] = 1;
        $where = $this->get_where($args);
        $field='*';
        if( isset($args['field']) && !empty($args['field']) ) $field = $args['field'];
        $sql = " SELECT {$field} FROM {$this->table} {$where['sql']}";
        echo $sql;
        echo "
";
        print_r($where['bind_data']);
        echo "
";
    }
}
$model = new lms_model();
$model->get_data( array('time_day_start' => '20160101','time_day_end' => 21231) );
$model->get_one( array('time_day_start' => '20160101','time_day_end' => 21231) );