1Z0-007多项选择题每日一练(2020.04.25)

多项选择题
Examine the SQL statement that creates ORDERS table:CREATE TABLE orders(SER_NO NUMBER UNIQUE,ORDER_ID NUMBER, ORDER_DATE DATE NOT NULL,STATUS VARCHAR2(10)CHECK (status IN ('CREDIT', 'CASH')),PROD_ID NUMBERREFERENCES PRODUCTS(PRODUCT_ID),ORD_TOTAL NUMBER,PRIMARY KEY (order_id, order_date));For which columns would an index be automatically created when you execute the above SQL statement? （）
A.SER_NO
B.ORDER_ID
C.STATUS
D.PROD_ID
E.ORD_TOTAL
F.composite index on ORDER_ID and ORDER_DATE
多项选择题
Which two are true about aggregate functions? （）
A. You can use aggregate functions in any clause of a SELECT statement.
B. You can use aggregate functions only in the column list of the SELECT clause and in the WHERE clause of a SELECT statement.
C. You can mix single row columns with aggregate functions in the column list of a SELECT statement by grouping on the single row columns.
D. You can pass column names, expressions, constants, or functions as parameters to an aggregate function.
E. You can use aggregate functions on a table, only by grouping the whole table as one single group.
F. You cannot group the rows of a table by more than one column while using aggregate functions.
多项选择题
Which two statements accurately describe a role?（）
A. A role can be given to a maximum of 1000 users.
B. A user can have access to a maximum of 10 roles.
C. A role can have a maximum of 100 privileges contained in it.
D. Privileges are given to a role by using the CREATE ROLE statement.
E. A role is a named group of related privileges that can be granted to the user.
F. A user can have access to several roles, and several users can be assigned the same role.
多项选择题
Which two statements about sequences are true? （）
A.You use a NEXTVAL pseudo column to look at the next possible value that would be generated from a sequence, without actually retrieving the value.
B.You use a CURRVAL pseudo column to look at the current value just generated from a sequence, without affecting the further values to be generated from the sequence.
C.You use a NEXTVAL pseudo column to obtain the next possible value from a sequence by actually retrieving the value from the sequence.
D.You use a CURRVAL pseudo column to generate a value from a sequence that would be used for a specified database column.
E.If a sequence starting from a value 100 and incremented by 1 is used by more than one application, then all of these applications could have a value of 105 assigned to their column whose value is being generated by the sequence.
F.You use a REUSE clause when creating a sequence to restart the sequence once it generates the maximum value defined for the sequence.
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.