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[问答题] 机械密封由几部分组成?

Examine the data in the EMPLOYEES and DEPARTMENTS tables: Also examine the SQL statements that create the EMPLOYEES and DEPARTMENTS tables: On the EMPLOYEES table, EMPLOYEE_ID is the primary key. MGR_ID is the ID of managers and refers to the EMPLOYEE_ID. DEPT_ID is foreign key to DEPARTMENT_ID column of the DEPARTMENTS table. On the DEPARTMENTS table, DEPARTMENT_ID is the primary key. Examine this DELETE statement: What happens when you execute the DELETE statement?() [" Only the row with department ID 40 is deleted in the DEPARTMENTS table."," The statement fails because there are child records in the EMPLOYEES table with department ID 40."," The row with department ID 40 is deleted in the DEPARTMENTS table. Also the rows with employee IDs 110 and 106 are deleted from the EMPLOYEES table."," The row with department ID 40 is deleted in the DEPARTMENTS table. Also the rows with employee IDs 106 and 110 and the employees working under employee 110 are deleted from the EMPLOYEES table."," The row with department ID 40 is deleted in the DEPARTMENTS table. Also all the rows in the EMPLOYEES table are deleted."," The statement fails because there are no columns specifies in the DELETE clause of the DELETE statement."] 采用环刀法测定压实度时,石灰土类基层每1000m2检查()。 ["1点","2点","3点","4点"] 若车辆仅在某种情况下在某段运营时间内上线工作,并且一日连续工作时间累计不超过一个工作班,则这种车辆称为()。 ["正班车","加班车","全程车","区间车"] 目前我国溶解气体共有()种。 ["1","2","3","4"] 赤松的雁行形态理论是什么? 机械密封由几部分组成?
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