php - MySql 嵌套选择变量在 PHP 中不起作用

Question

我有一个嵌套的 mysql 查询，可以为我提供每 6 行单个表列 (poutput_edat) 的平均值

    set @rownum := 0;
    set @sum := 0;

    SELECT the_avg FROM (   
    select poutput_edat,   @rownum := (@rownum + 1) as rownum,    
    @sum := IF(@rownum mod 6 = 1,0 + poutput_edat,@sum + poutput_edat)
    as running_sum,   IF(@rownum mod 6 = 0,@sum / 6,NULL) as the_avg   
    from raw_edat /*WHERE date_edat = CURDATE()*/ ORDER BY invTime_edat desc)
    as average

我在使用 php mysqli 进行此查询时遇到问题，它可以完美地直接查询数据库。这是 php mysql 的限制吗？

吉米

Answer 1

您可以尝试在单独的 FROM 子句中声明变量吗，例如:

SELECT the_avg FROM (   
    select poutput_edat,   @rownum := (@rownum + 1) as rownum,    
    @sum := IF(@rownum mod 6 = 1,0 + poutput_edat,@sum + poutput_edat)
    as running_sum,   IF(@rownum mod 6 = 0,@sum / 6,NULL) as the_avg   
    FROM raw_edat /*WHERE date_edat = CURDATE()*/, (SELECT @rownum := 0, @sum := 0) a 
    ORDER BY invTime_edat desc)
    as average