Which two statements about views are true?（）A、A view can be created as read only.B、A view can be created as a join on two or more tables.C、A view cannot have an ORDER BY clause in the SELECT statement.D、A view cannot be created with a GROUP BY clause in t

第1题：

Which two statements are true regarding views?（）

• A、A subquery that defines a view cannot include the GROUP BY clause 
• B、A view that is created with the subquery having the DISTINCT keyword can be updated 
• C、A view that is created with the subquery having the pseudo column ROWNUM keyword cannot be updated 
• D、A data manipulation language (DML) operation can be performed on a view that is created with the subquery having all the NOT NULL columns of a table

第2题：

Which two statements about subqueries are true? （）

• A、A subquery should retrieve only one row.
• B、A subquery can retrieve zero or more rows.
• C、A subquery can be used only in SQL query statements.
• D、Subqueries CANNOT be nested by more than two levels.
• E、A subquery CANNOT be used in an SQL query statement that uses group functions.
• F、When a subquery is used with an inequality comparison operator in the outer SQL statement, the column list in the SELECT clause of the subquery should contain only one column.

第3题：

第4题：

Which two statements are true about simple views？（）

• A、Views can be created as read only.
• B、Views are data segments like tables.
• C、Views can be created on the basis of more than one table.
• D、Data manipulation language （DML） operations cannot be performed on views.

第5题：

What is true about updates through a view? （）

• A、You cannot update a view with group functions.
• B、When you update a view group functions are automatically computed.
• C、When you update a view only the constraints on the underlying table will be in effect.
• D、When you update a view the constraints on the views always override the constraints on the underlying tables.

第6题：

Which two statements are true about WHERE and HAVING clauses? （）

• A、A WHERE clause can be used to restrict both rows and groups.
• B、A WHERE clause can be used to restrict rows only.
• C、A HAVING clause can be used to restrict both rows and groups.
• D、A HAVING clause can be used to restrict groups only.
• E、A WHERE clause CANNOT be used in a query of the query uses a HAVING clause.
• F、A HAVING clause CANNOT be used in subqueries.

第7题：

Which two statements are true regarding the ORDER BY clause? （）

• A、It is executed first in the query execution 
• B、It must be the last clause in the SELECT statement 
• C、It cannot be used in a SELECT statement containing a HAVING clause
• D、You cannot specify a column name followed by an expression in this clause 
• E、You can specify a combination of numeric positions and column names in this clause

第8题：

第9题：

Which best describes an inline view?（）

• A、a schema object
• B、a subquery that can contain an ORDER BY clause
• C、another name for a view that contains group functions
• D、a subquery that is part of the FROM clause of another query

第10题：

Which two statements are true regarding the USING and ON clauses in table joins?（）

• A、Both USING and ON clauses can be used for equijoins and nonequijoins 
• B、Amaximum of one pair of columns can be joined between two tables using the ON clause 
• C、The ON clause can be used to join tables on columns that have different names but compatible data types 
• D、The WHERE clause can be used to apply additional conditions in SELECT statements containing the ON or the USING clause