如果我在where子句中应用静态数据,它比应用子查询更快。示例:SELECT STARTDATE, ENDDATE FROM TEST WHERE STARTDATE = '2012-08-21';SELECT STARTDATE, ENDDATE FROM TEST WHERE STARTDATE = (SELECT STARTDATE FROM TEST2 LIMIT 1);子查询每次执行一次比较,对每条记录执行查询,还是只执行1次?
我有一个mysql表,如下所示:当访问者访问网站时,它将访问者id和页面id存储为一行。SELECT COUNT(visid),visid FROM vislog GROUP BY visid ORDER BY COUNT(visid) DESC
但我不知道下一步该怎么计算可以像MySQL查询一样做吗?