MYSQL 1Z0-874 問題集 : MySQL 5.0 Database Administrator Certified Professional Exam, Part II

Which factors can be considered in a stored routine to allow or disallow access or modification of data? (Choose two)

• A. The identity of the client user
• B. The current date and time
• C. The CPU load of the system
• D. The number of current connections

Which of the following statements best describe the indexes supported by the MEMORY storage engine, and their general characteristics?

• A. MEMORY tables support HASH indexes which provide better performance with non-unique index values and other comparison operators, and BTREE indexes which provide fast lookups that use a unique index.
• B. MEMORY tables support HASH indexes which provide fast lookups that use a unique index, and BTREE indexes which provide better performance with non-unique index values and other comparison operators.
• C. MEMORY tables only support HASH indexes which provide fast lookups that use a unique index.
• D. MEMORY tables only support BTREE which provide better performance with non-unique index values and other comparison operators.

Consider the following: mysql> EXPLAIN SELECT DISTINCT City.id,City.name -> FROM City,Country -> WHERE Country.Name IN ('United States','Canada','Mexico') -> AND City.CountryCode=Country.Code -> ORDER BY name *************************** 1. row *************************** id: 1 select_type: SIMPLE table: City type: ALL possible_keys: NULL key: NULL key_len: NULL ref: NULL rows: 4079 Extra: Using temporary; Using filesort *************************** 2. row *************************** id: 1 select_type: SIMPLE table: Country type: eq_ref possible_keys: PRIMARY key: PRIMARY
key_len: 3
ref: world.City.CountryCode
rows: 1
Extra: Using where;
Distinct
Which of the following best describes the meaning of the values in the ref columns?

• A. No index columns are used to choose rows from Country and the City.CountryCode column is used to reference rows in the City table.
• B. No indexed columns are used to choose rows from City and the City.CountryCode column is used to reference rows in the Country table.
• C. City.CountryCode is used to sort what rows are returned from the City table.

Consider the following:
mysql> DESC customers;
+--------+------------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+--------+------------------+------+-----+---------+----------------+
| id | int(11) unsigned | NO | PRI | NULL | auto_increment |
| name_1 | char(20) | YES | MUL | NULL | |
| name_2 | varchar(20) | YES | | NULL | |
| name_3 | varchar(20) | YES | | NULL | |
| email | varchar(50) | YES | | NULL | |
+--------+------------------+------+-----+---------+----------------+
mysql> EXPLAIN SELECT * FROM customers WHERE name_1 = 'Johnny'
*************************** 1. row ***************************
id: 1
select_type: SIMPLE
table: customers
type: ref
possible_keys: i_name_1_01,i_name_1_02
key: i_name_1_01
key_len: 21
ref: const
rows: 1
Extra: Using where
What can be assumed by looking at the key_len column?

• A. The longest index is 21 characters long.
• B. The full index is being used.
• C. The partial index is being used.
• D. No indexes are being used.

Why should you be selective when granting the SUPER privilege to an account? (Choose two)

• A. Because it allows a client to kill other client connections.
• B. Because it allows a client to shutdown the server.
• C. Because it allows client accounts to takeover other client accounts.
• D. Because it allows changing of the server runtime configuration.