单项选择题
Which is an /SQL*Plus command? （）
A. INSERT
B. UPDATE
C. SELECT
D. DESCRIBE
E. DELETE
F. RENAME
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相关考题
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单项选择题
Which SELECT statement should you use to extract the year from the system date and display it in the format "1998"? （）
A. SELECT TO_CHAR(SYSDATE,'yyyy') FROM dual;
B. SELECT TO_DATE(SYSDATE,'yyyy') FROM dual;
C. SELECT DECODE(SUBSTR(SYSDATE, 8), 'YYYY') FROM dual;
D. SELECT DECODE(SUBSTR(SYSDATE, 8), 'year') FROM dual;
E. SELECT TO_CHAR(SUBSTR(SYSDATE, 8,2),'yyyy') FROM dual; -
单项选择题
The EMPLOYEES table contains these columns: LAST_NAME VARCHAR2 (25) SALARY NUMBER (6,2) COMMISSION_PCT NUMBER (6) You need to write a query that will produce these results: 1. Display the salary multiplied by the commission_pct. 2. Exclude employees with a zero commission_pct. 3. Display a zero for employees with a null commission value. Evaluate the SQL statement: SELECT LAST_NAME, SALARY*COMMISSION_PCT FROM EMPLOYEES WHERE COMMISSION_PCT IS NOT NULL; What does the statement provide? （）
A. All of the desired results
B. Two of the desired results
C. One of the desired results
D. An error statement -
单项选择题
A subquery can be used to （）.
A. Create groups of data
B. Sort data in a specific order
C. Convert data to a different format
D. Retrieve data based on an unknown condition
