A data dictionary is a special file that contains A. the names of all fields in all files B. the data types of all fields in all files C. the widths of all fields in all files D. All of the above E. None of the above

The correct answer is: D. All of the above

A data dictionary is a special file that contains the names, data types, and widths of all fields in all files. It is used to document the structure of a database and to help users understand the data that is stored in it.

The names of the fields in a data dictionary are used to identify the data that is stored in each field. The data types of the fields are used to specify the type of data that can be stored in each field. The widths of the fields are used to specify the number of characters that can be stored in each field.

A data dictionary is an important tool for database management. It helps to ensure that the data in a database is accurate and consistent. It also helps to make it easier to find and use the data in a database.

Here is a brief explanation of each option:

• A. The names of all fields in all files

The names of the fields in a data dictionary are used to identify the data that is stored in each field. For example, the name of a field might be “Customer Name” or “Order Date”.

• B. The data types of all fields in all files

The data types of the fields in a data dictionary are used to specify the type of data that can be stored in each field. For example, the data type of a field might be “text”, “number”, or “date”.

• C. The widths of all fields in all files

The widths of the fields in a data dictionary are used to specify the number of characters that can be stored in each field. For example, the width of a field might be 255 characters or 10 digits.