1.GROUP BY GROUP BY 函数就是 SQL 中用来实现分组的函数,其用于结合聚合函数,能根据给定数据列的每个成员对查询结果进行分组统计,最终得到一个分组汇总表。
mysql> SELECT country, COUNT(country) AS teacher_count-> FROM teacher…
【OH】SET System Variable Summary SQLPLUS 系统变量设置 SET System Variable Summary System Variable Description SET APPI[NFO]{ON |?OFF?|?text} Sets automatic registering of scripts through the DBMS_APPLICATION_INFO package. SET ARRAY[SIZE]…