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Selectcount（*）from employee语句得到的结果是（）。
- A、某个记录的信息
- B、全部记录的详细信息
- C、所有记录的条数
- D、得到3条记录
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更多 “Selectcount（*）from employee语句得到的结果是（）。A、某个记录的信息B、全部记录的详细信息C、所有记录的条数D、得到3条记录” 相关考题
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Examine the structure of the EMPLOYEES and NEW_EMPLOYEES tables: EMPLOYEES EMPLOYEE_ID NUMBER Primary Key FIRST_NAME VARCHAR2(25) LAST_NAME VARCHAR2(25) HIRE_DATE DATE NEW_EMPLOYEES EMPLOYEE_ID NUMBER Primary Key NAME VARCHAR2 (60) Which DELETE statement is valid?（）A、DELETE FROM employees WHERE employee_id = (SELECT employee_id FROM employees);B、DELETE * FROM employees WHERE employee_id = (SELECT employee_id FROM new_ employees);C、DELETE FROM employees WHERE employee_id IN (SELECT employee_id FROM new_employees WHERE name = 'carrey');D、DELETE * FROM employees WHERE employee_id IN (SELECT employee_id FROM new_employees WHERE name = 'carrey');
考题
单选题SQL语句“select count（*）from employee”，需要SqlCommand对象的哪一个方法在执行（）。A
ExecuteNonQuery（）B
ExecuteScalar（）C
EndExecuteReader（）D
ExecuteXmlReader（）
考题
单选题Examine the structure of the EMPLOYEES and NEW_EMPLOYEES tables: EMPLOYEES EMPLOYEE_ID NUMBER Primary Key FIRST_NAME VARCHAR2 (25) LAST_NAME VARCHAR2 (25) HIRE_DATE DATE NEW EMPLOYEES EMPLOYEE_ID NUMBER Primary Key NAME VARCHAR2 (60) Which DELETE statement is valid? （）A
DELETE FROM employees WHERE employee_id = (SELECT employee_id FROM employees);B
DELETE * FROM employees WHERE employee_id = (SELECT employee_id FROM new_ employees);C
DELETE FROM employees WHERE employee_id IN (SELECT employee_id FROM new_employees WHERE name = ('Carrey')'D
DELETE * FROM employees WHERE employee_id IN (SELECT employee_id FROM new_employees WHERE last_ name = ('Carrey')'
考题
单选题What type of constraint is used to ensure that each row inserted into the EMPLOYEE table with a value in the WORKDEPT column has a row with a corresponding value in the DEPTNO column of the DEPARTMENT table?（）A
A check constraint on the EMPLOYEE tableB
A unique constraint on the EMPLOYEE table WORKDEPT columnC
A foreign key reference from the DEPARTMENT tables DEPTNO column to the WORKDEPT column of the EMPLOYEE tableD
A foreign key reference from the EMPLOYEE tables WORKDEPT column to the DEPTNO column of the DEPARTMENT table
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