MSSql改Mysql

Question

SELECT
    *
FROM
    (SELECT
        left(charge,4) as charge,
        date(stattime) as stattime,
        count(*) as num
    FROM
        Table
    WHERE
        ((left(charge,3)='spc' or left(charge,3)='spw'  or left(charge,3)='spm')) AND
        stattime>='2011-06-01'
    GROUP BY
        left(charge,4),
        date(stattime) 
    ) a pivot (max(num) for charge in (spca,spcb,spcc,spcd,spwb,spma,spmb,spmc,spmd)) b求改成mysql

Answer 1

MYSQL中没有pivot，用SUM(IF()) OR SUM(CASE WHEN)，动手做一下吧，有问题再问

Answer 2

SELECT
    sum(if(charge='spc',num,0)) as spc,
    sum(if(charge='spw,num,0)) as spw
FROM
    (SELECT
        left(charge,4) as charge,
        date(stattime) as stattime,
        count(*) as num
    FROM
        Table
    WHERE
        ((left(charge,3)='spc' or left(charge,3)='spw'  or left(charge,3)='spm')) AND
        stattime>='2011-06-01'
    GROUP BY
        left(charge,4),
        date(stattime) 
    ) a是不是这样写的？问下
sum(if(charge='spw,num,0)) as spw
这个0的含义是什么呀？