一、原题 Which statements are correct regarding indexes? (Choose all that apply.) A. When a table is dropped, the corresponding indexes are automatically dropped. B. A FOREIGN KEY constraint on a column in a table automatically creates a nonunique index.…

49.Include和require的区别 require 外部文件如果不存在，会报错，后面的代码不会执行 Include 外部文件如果不存在，会报错，后面的代码继续执行include_once()和require_once()在加载之前要判断是否已经导入 50、索引的建立与使用索…

一、原题 Which two statements are true regarding constraints? (Choose two.) A. A table can have only one primary key and one foreign key. B. A table can have only one primary key but multiple foreign keys. C. Only the primary key can be defined at the col…