例如下面的sql，应该首先添加where条件下apfi.file_id =5082字段的索引，
其次添加bp.single_file_id的字段索引
?
sql如下：
SELECT apfi.sw, apfi.sh, apfi.cx, apfi.cy, bp.buy_url, bp.discount_price AS price, bp.price AS old_price, bp.id AS product_id, CONCAT('single_', sys_item_id) AS idFROM app_polly_file_item apfiINNER JOIN b_product bp ON apfi.sys_item_id = bp.single_file_idAND bp.deleted = 0AND bp.available = 1WHERE apfi.file_id =5082AND apfi.type = 'sys'AND apfi.sys_item_type = 'single'ORDER BY apfi.sys_item_id?