Question 1

In a hierarchical form,the fixed part is called the parent form and the variable part is called the child form.

Accepted Answer

In a hierarchical form, the fixed part is typically referred to as the "parent" and the variable part as the "child," but these terms describe the relationship between levels rather than specific parts being fixed or variable. The terms "parent" and "child" indicate a hierarchical relationship where the parent can have one or more children, but do not inherently define one as fixed and the other as variable.

Question 2

SQL:1999 specifies that a view can be used in any query.

Accepted Answer

SQL:1999 does indeed specify that a view can be used in any query.

Question 3

Typically in a hierarchical form,the data from the two 1-M tables shown on the main form and the subform would be the result of executing a join query on the two tables for a specific value of the foreign key.

Accepted Answer

This is true. The main form displays data from the primary table and the subform displays data from a related table, linked by a foreign key. The subform's data is typically the result of executing a join query on the two tables for a specific value of the foreign key.

Question 4

Although there are many advantages to using views,the main drawback is that performance can sometimes be poor in processing some complex views.

Accepted Answer

Views often involve complex queries and can impact performance if not optimized properly.

Question 5

The same rules of updatability apply to 1-M queries with more than two tables,but you must apply the rules to each join in the query.

Accepted Answer

When dealing with 1-M queries with more than two tables, it is important to apply the rules of updatability to each join in the query. This ensures that the query can be updated without causing any conflicts, and allows for the database to remain consistent and accurate. Therefore, the statement "the same rules of updatability apply to 1-M queries with more than two tables, but you must apply the rules to each join in the query" is true.

Question 6

Using the materialization strategy,when a user submits a query using a view,the query defining the view is first executed creating a temporary table,and then the query using the view is executed on the temporary table.

Accepted Answer

This is correct. The materialization strategy involves creating a temporary table based on the view definition before executing the user's query. This can improve query performance by precomputing and storing the view results.

Question 7

You can rename some of the columns,all of the columns,or none of the columns in a view using parentheses after the view name.

Accepted Answer

In SQL, you cannot rename columns in a view using parentheses after the view name. Column aliases must be defined in the SELECT statement within the view definition.

Question 8

The motivations for using views are that they support data independence,simplify query formulation,and provide flexible security.

Accepted Answer

Views in a database allow users to access data in a more organized and controlled way. They can help protect sensitive data by limiting access to certain fields or rows, while also making it easier to write complex queries by breaking them down into smaller, more manageable pieces. Additionally, views can be used to abstract away changes to the underlying tables, making the application more data independent.

Question 9

A single-table view is not updatable if all of the columns of the base table are not included in the view.

Accepted Answer

A single-table view can be updatable even if not all columns of the base table are included in the view, as long as the view includes all columns that are part of the primary key or required for the update operation to comply with any NOT NULL constraints.

Question 10

A modification query may cause rows in a view to disappear if a column in the WHERE clause of the view definition is changed by an UPDATE statement.

Accepted Answer

When a modification query such as UPDATE is executed on a view that contains a WHERE clause, if the column in the WHERE clause is modified, some rows may no longer meet the criteria and will disappear from the view.

Question 11

In a 1-M updatable query,you cannot insert a row into the parent table without also inserting a corresponding row into the child table.

Accepted Answer

In a 1-M (one-to-many) updatable query, inserting a row into the parent table does not require simultaneously inserting a corresponding row into the child table. The relationship constraint typically ensures that if a row in the child table exists, it must have a corresponding parent row, but it does not prevent the parent table from having rows without corresponding child rows.

Question 12

In a 1-M updatable query,to insert a row into the child table,you would provide only the values needed to insert a row into the child table.

Accepted Answer

Yes, in a 1-M updatable query, to insert a row into the child table, you would only need to provide the values needed to insert a row into the child table. This is because the relationship between the parent and child table is already established, so the necessary foreign key values are already known.

Question 13

In a data warehouse environment,views are materialized on demand,i.e.when the view query is submitted.

Accepted Answer

In a data warehouse environment, views can be materialized in advance and stored physically to speed up query processing. They are not necessarily materialized on demand when the query is submitted.

Question 14

Modifications to views,such as deleting rows or changing the primary key column are subject to the integrity rules of the underlying base table.

Accepted Answer

Modifying views can impact the underlying base table, so the changes must comply with the integrity constraints set on the base table. If the modifications violate the constraints, the database management system will not allow them to be executed.

Question 15

Only single-table views are updatable with SQL modification statements.

Accepted Answer

Views can be updatable even if they are based on multiple tables, as long as certain conditions are met, such as the view being defined with a simple SELECT statement and the modification not violating any integrity constraints.

Question 16

The WITH RESTRICTIONS OPTION clause of the CREATE VIEW statement prevents side effects from occurring when a view is updated.

Accepted Answer

The WITH CHECK OPTION clause of the CREATE VIEW statement ensures that all data modifications performed through the view adhere to the criteria set by the view's SELECT statement, not preventing side effects but ensuring data integrity.

Question 17

If a table name used in a view is changed,the view definition does not have to be changed but the applications using the view must be changed.

Accepted Answer

When a table name used in a view is changed, the view definition must be updated to reflect the new table name; otherwise, the view will not work properly. Applications using the view do not necessarily need to be changed if they refer to the view by name and the view's interface (columns) remains the same.

Question 18

In a 1-M updatable query,update operations are supported on the parent table even if the query does not contain the primary key of the parent table.

Accepted Answer

In a 1-M updatable query, update operations are supported on the parent table using a foreign key even if the primary key is not explicitly included in the query.

Question 19

In a hierarchical form involving a 1-M relationship,only columns from the two tables involved in the relationship can be displayed in the form.

Accepted Answer

In a hierarchical form involving a 1-M relationship, columns from both the primary and foreign key tables can be displayed, along with any other necessary columns from related tables.

Question 20

In a 1-M updatable query,to insert a row into both the parent and child tables,you must supply the primary keys and all the required columns of both the parent and child tables.

Accepted Answer

This is because you cannot insert a row in the child table without first inserting a row in the parent table, and to do so, you must supply the primary key of the parent table. Additionally, you must supply all the required columns of both tables to ensure data integrity.

Quiz 10: Application Development With Views