单项选择题
In which scenario would index be most useful?（）
A. The indexed column is declared as NOT NULL.
B. The indexed columns are used in the FROM clause.
C. The indexed columns are part of an expression.
D. The indexed column contains a wide range of values.
相关考题
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单项选择题
The EMPLOYEES table contains these columns: EMPLOYEE_ID NUMBER(4) LAST_NAME VARCHAR2 (25) JOB_ID VARCHAR2(10) You want to search for strings that contain SA_ in the JOB_ID column. Which SQL statement do you use?（）
A. SELECT employee_id, last_name, job_id FROM employees WHERE job_id LIKE '%SA\_%'ESCAPE'\';
B. SELECT employee_id, last_name, job_id FROM employees WHERE job_id LIKE '%SA_';
C. SELECT employee_id, last_name, job_id FROM employees WHERE job_id LIKE '%SA_'ESCAPE'\';
D. SELECT employee_id, last_name, job_id FROM employees WHERE job_id '%SA_'; -
单项选择题
Examine the structure of the EMPLOYEES table: You issue these statements: At the end of this transaction, what is true?（）
A. You have no rows in the table.
B. You have an employee with the name of James.
C. You cannot roll back to the same savepoint more than once.
D. Your last update fails to update any rows because employee ID 180 was already eleted. -
单项选择题
The user Sue issues this SQL statement: GRANT SELECT ON sue. EMP TO alice WITH GRANT OPTION; The user Alice issues this SQL statement: GRANT SELECT ON sue. EMP TO reena WITH GRANT OPTION; The user Reena issues this SQL statement: GRANT SELECT ON sue. EMP TO timber; The user Sue issues this SQL statement: REVOKE select on sue. EMP FROM alice; For which users does the revoke command revoke SELECT privileges on the SUE.EMP table?（）
A. Alice only
B. Alice and Reena
C. Alice, Reena, and Timber
D. Sue, Alice, Reena, and Timber
