多项选择题
Which three statements correctly describe the functions and use of constraints? （）
A.Constraints provide data independence.
B.Constraints make complex queries easy.
C.Constraints enforce rules at the view level.
D.Constraints enforce rules at the table level.
E.Constraints prevent the deletion of a table if there are dependencies.
F.Constraints prevent the deletion of an index if there are dependencies.
相关考题
-
单项选择题
Evaluate the SQL statement:SELECT ROUND(TRUNC(MOD(1600,10),-1),2)FROM dual;What will be displayed?（）
A.0
B.1
C.0.00
D.an error statement -
单项选择题
Which SQL statement displays the date March 19, 2001 in a format that appears as "Nineteenth of March 2001 12:00:00 AM"?（）
A.SELECT TO_CHAR(TO_DATE('19-Mar-2001', 'DD-Mon-YYYY'), 'fmDdspth "of" Month YYYY fmHH:MI:SS AM') NEW_DATE FROM dual;
B.SELECT TO_CHAR(TO_DATE('19-Mar-2001', 'DD-Mon-YYYY'), 'Ddspth "of" Month YYYY fmHH:MI:SS AM') NEW_DATE FROM dual;
C.SELECT TO_CHAR(TO_DATE('19-Mar-2001', 'DD-Mon-YYYY'), 'fmDdspth "of" Month YYYY HH:MI:SS AM') NEW_DATE FROM dual;
D.SELECT TO_CHAR(TO_DATE('19-Mar-2001', 'DD-Mon-YYYY'), 'fmtDdspth "of" Month YYYY fmtHH:MI:SS AM') NEW_DATE FROM dual; -
单项选择题
In which scenario would an 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.
