单项选择题
A. Removes the table B. Removes all rows from a table C. Shortens the table to 10 rows D. Removes all columns from a table E. Removes foreign keys from a table
Which is an /SQL*Plus command?（）A. INSERTB. UPDATEC. SE...
单项选择题Which is an /SQL*Plus command?（）
A. INSERT B. UPDATE C. SELECT D. DESCRIBE E. DELETE F. RENAME
Examine the data of the EMPLOYEES table. EMPLOYEES (EMP...
Examine the data of the EMPLOYEES table. EMPLOYEES (EMPLOYEE_ID is the primary key. MGR_ID is the ID of managers and refers to the EMPLOYEE_ID) Evaluate this SQL statement: What is its output?（）
A. B. C. D. E. The SQL statement produces an error.
Which SELECT statement should you use to extract the ye...
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;
