Evaluate the CREATE TABLE statement： 
 CREATE TABLE products  
（product_id NUMBER （6） 
CONSTRAINT prod_id_pk PRIMARY KEY，  product_name VARCHAR2 （15））；  
Which statement is true regarding the PROD_ID_PK constraint？（）

多项选择题Whichtwostatementsaretrueregardingtheexecutionofthecorrelatedsubqueries？（）

A. The nested query executes after the outer query returns the row.
B. The nested query executes first and then the outer query executes.
C. The outer query executes only once for the result returned by the inner query.
D. Each row returned by the outer query is evaluated for the results returned by the inner query.

单项选择题View the Exhibit and examine the structure of the ORDERS and ORDERJTEMS tables.  Evaluate the following SQL statement：   SELECT oi.order_id， product_jd， order_date   FROM order_items oi JOIN orders o   USING （order_id）；   Which statement is true regarding the execution of this SQL statement？（）

A. The statement would not execute because table aliases are not allowed in the JOIN clause.
B. The statement would not execute because the table alias prefix is not used in the USING clause.
C. The statement would not execute because all the columns in the SELECT clause are not prefixed with table aliases.
D. The statement would not execute because the column part of the USING clause cannot have a qualifier in the SELECT list.

多项选择题Whichthreestatementsaretrueregardingsingle-rowfunctions？（）

A. They can accept only one argument.
B. They can be nested up to only two levels.
C. They can return multiple values of more than one data type.
D. They can be used in SELECT， WHERE， and ORDER BY clauses.  
E. They can modify the data type of the argument that is referenced.
F. They can accept a column name， expression， variable name， or a user-supplied constant as arguments.

多项选择题WhichthreetaskscanbeperformedusingregularexpressionsupportinOracleDatabase10g？（）

A. it can be used to concatenate two strings.
B. it can be used to find out the total length of the string.
C. it can be used for string manipulation and searching operations.
D. it can be used to format the output for a column or expression having string data.
E. it can be used to find and replace operations for a column or expression having string data.

单项选择题EMPDET is an external table containing the columns EMPNO and ENAME.   Which command would work in relation to the EMPDET table？ （）

A.A
B.B
C.C
D.D