WaveBridge的博客

子查询的一些语句实例:SELECT * FROM t1 WHERE column = (SELECT column FROM t2); 求平均数，并四舍五入保留两位小数:SELECT ROUND(AVG(number),2) FROM table; 查询大于平均数的项,并且按照number的降序排列:SELECT id,name,number FROM table WHERE number > (