127 CHAPTER 4 RELATIONAL DATABASES 6. With respect to database systems, which of the following statement(s) is (are) true? a. The physical view of data is how people conceptually organize and understand the relationships among data items. b. The DML builds the data dictionary, creates the database, describes logical views for cach user, and specifies security constraints. c. A record layout shows the items stored in a file, including the type of data stored and both the order and length of the data fields. d. A DBMS allows users to query or update a database without knowing where data are actually stored c. The external-level schema is the organization-wide view of a database and lists all data elements and the relationships among them. 7. With respect to database systems, which of the following statement(s) is (are) true? a. The DDL and DML should be restricted to authorized administrators and program- mers; the DOL is available to users. b. A report writer is a high-level, English-like language with powerful, easy-to-use com- mands to help sort, order, and update data. c. DBMS software links the way data are physically stored with each user's logical view of the data. d. A subschema can prevent access to those portions of the database that do not apply to it. e. An individual user's view of portions of a database is referred to as an internal-level schema 8. With respect to relational databases, which of the following statement(s) is (are) true? a. The referential integrity rule ensures that there are no update anomaly problems with the foreign keys. b. A delete anomaly occurs when deleting a row has unintended consequences. c. Each relational table row is called a couple and contains data about a specific item in the table; each column contains data about an attribute of that item, d. The normalization process is used to create a set of relational tables in 3NE e. In a relational database, there can be no more than two values per cell. 9. With respect to relational databases, which of the following statement(s) is (are) true? a. A foreign key is only found in one table; it is not allowed to be in another table. b. When data about objects of interest are stored in separate database tables, it is easier to avoid insert anomalies. c. Semantic data modeling uses a system designer's knowledge of business processes to create tables in 3NE. d. According to the entity integrity rule, a primary key can uniquely identify a table row if it is blank e. An insert anomaly occurs when there is no way to update records to a database. CASE 4-1 Research Project As in all areas of IT, DBMSs are constantly chang- ing and improving. Research how businesses are using DBMSs, and write a report of your findings. Address the following issues: 1. Which popular DBMS products are based on the re- 2. Which DBMS products are based on a log model other than the relational data model? 3. What are the relative strengths and weakness the different types (relational versus other lo models) of DBMSS