In which scenario， will you issue the following command？（） RMAN> REPORT NEED BACKUP DAYS 7； to configure RMAN to maintain backup information in the RMAN repository for seven days。 to configure RMAN to maintain backup information in the control file for at least seven days。 to display the list of files that have not been backed up for the last seven days。 to display the list of files that must be backed up within seven day。
氮源
Examine the data in the EMPLOYEES table. On the EMPLOYEES table, EMPLOYEE_ID is the primary key. MGR_ID is the ID of managers and refers to the EMPLOYEE_ID. The JOB_ID column is a NOT NULL column. Evaluate this DELETE statement: Why does the DELETE statement fail when you execute it?（） There is no row with dept_id 90 in the EMPLOYEES table.。 You cannot delete the JOB_ID column because it is a NOT NULL column.。 You cannot specify column names in the DELETE clause of the DELETE statement.。 You cannot delete the EMPLOYEE_ID column because it is the primary key of the table.。
在保护接零的中性线，必须（）。 一点接地。 多点接地。 不接地。
简述创设游戏场地的基本要求。
变更的类型通常可以划分为哪几类（）
