MySQL实战基础知识入门(3)：近7日销量合计php后端mysql语句如果当日为空则自动补0的解决方案

    public function getEveryDay()
    {
        global $db, $res;
        dbc();
        $NowTimes = date("Y-m-d", time());
        $sql = "select DATE_FORMAT(paid_at,'%Y-%m-%d') as dataKey,ifnull(COUNT(id),0) AS totalTrans,ifnull(SUM(should_paid),0) AS totalPays from (
                SELECT \"" . $NowTimes . "\" as evData
                union all
                SELECT date_sub(\"" . $NowTimes . "\", interval 1 day) as evData
                union all
                SELECT date_sub(\"" . $NowTimes . "\", interval 2 day) as evData
                union all
                SELECT date_sub(\"" . $NowTimes . "\", interval 3 day) as evData
                union all
                SELECT date_sub(\"" . $NowTimes . "\", interval 4 day) as evData
                union all
                SELECT date_sub(\"" . $NowTimes . "\", interval 5 day) as evData
                union all
                SELECT date_sub(\"" . $NowTimes . "\", interval 6 day) as evData) as total LEFT JOIN " . $db->table('orders') . " ev on DATE_FORMAT(ev.paid_at,'%Y-%m-%d') = total.evData ";
        $sql .= " GROUP BY evData";
        $row = $db->queryall($sql);
        $res["data"] = $row;
        die(json_encode_lockdata($res));
    }

JSON数据格式化

{
	"err": "",
	"res": "",
	"data": [{
		"dataKey": "2020-07-23",
		"totalTrans": "93",
		"totalPays": "3577.16"
	}, {
		"dataKey": "2020-07-24",
		"totalTrans": "106",
		"totalPays": "3313.11"
	}, {
		"dataKey": "2020-07-25",
		"totalTrans": "110",
		"totalPays": "3442.04"
	}, {
		"dataKey": "2020-07-26",
		"totalTrans": "96",
		"totalPays": "2890.99"
	}, {
		"dataKey": "2020-07-27",
		"totalTrans": "119",
		"totalPays": "3669.60"
	}, {
		"dataKey": "2020-07-28",
		"totalTrans": "135",
		"totalPays": "4262.56"
	}, {
		"dataKey": "2020-07-29",
		"totalTrans": "48",
		"totalPays": "1280.88"
	}]
}

Done!