我希望在mysql中使用来自单个表的单个查询来跟踪输出。Total Pending Critical Completed现在,我正在对不同的列使用4个查询,如select count(*) as Pending from Y where status = 0--- for secondcolumn
select count(*) as cr
在条件允许的情况下,可以根据这个列过滤列吗?我需要计算每个生命周期中不同ids的数量。例如,如果生存期= 10,则需要在生存期介于10至30之间的范围内计算所有唯一is。如果我写 lifetime, FROM lifetime_countCOUNT(DISTINCT id_ru) AS number
FROM lifetime_<em
我们确切地知道count(*)比mysql_num_rows快,但是足够快吗?$sql="SELECT COUNT('x') as num FROM firma where 1 and firma.onay=1 and firma.bireysel=0 ";$row= mysqli_fetch_row($res);此查