Microsoft Exam 77-885 Topic 2 Question 30 Discussion

The following features of a table help a user in retrieving data more quickly:

Primary key: A table usually has a column or combination of columns whose values uniquely identify each row in the table. This column (or columns) is called the primary key. Primary key ensures that no duplicate or null values are entered in the column (or columns) defined as primary key columns. This enforces integrity of the table. A primary key can be created by defining a primary key constraint while creating or altering a table. A table can have only one primary key constraint. As primary key constraints ensure uniqueness, they are often defined by using an identity column.

Index: In Microsoft Office Access 2010, an index is a list of field values included in a table. It helps Access in finding and sorting records quickly. An index stores the record's location based on the columns that are part of the index. The indexed fields have unique values which make it more efficient and faster for Access to read and find a specific field value.

Answer B is incorrect. An input mask is used to control values of a field entered by a database user. The input mask includes literal characters, for example, space, dot, parenthesis, and placeholder. Microsoft Office Access contains a number of pre-defined input masks that match with most of the conditions. A user can create customized masks according to his needs. The Input Mask Wizard is used to create an input mask for text and date fields. If the user wants to create an input mask for numeric fields, he should enter the formatting symbol himself.

Answer D is incorrect. A validation rule is a set of rules associated with a column so that a user is restricted from entering invalid data.