Chapter 7 (True/False)

1. A database language enables the user to create database and table structures to perform basic data management chores.

2. A database language enables the user to perform complex queries designed to transform the raw data into useful information.

3. The ANSI prescribes a standard SQL–the current fully approved version is known as SQL-07.

4. The ANSI SQL standards are also accepted by the ISO.

5. SQL is considered difficult to learn; its command set has a vocabulary of more than 300 words.

6. Data type selection is usually dictated by the nature of the data and by the intended use.

7. Only numeric data types can be added and subtracted in SQL.

8. Entity integrity is enforced automatically when the primary key is specified in the CREATE TABLE command sequence.

9. The CHECK constraint is used to define a condition for the values that the attribute domain cannot have.

10. SQL requires the use of the ADD command to enter data into a table.

11. You cannot insert a row containing a null attribute value using SQL

12. To list the contents of a table, you must use the DISPLAY command.

13. Any changes made to the contents of a table are not physically saved on disk until you use the SAVE<table name> command.

14. The COMMIT command does not permanently save all changes. In order to do that, you must use SAVE

15. If you have not yet used the COMMIT command to store the changes permanently in the database, you can restore the database to its previous condition with the ROLLBACK command.

16. All SQL commands must be issued on a single line

17. Although SQL commands can be grouped together on a single line, complex command sequences are best shown on separate lines, with space between the SQL command and the command’s components.

18. You can select partial table contents by naming the desired fields and by placing restrictions on the rows to be included in the output.

19. Oracle users can use the Access QBE (query by example) query generator.

20. Since computers identify all characters by their numeric codes, mathematical operators cannot be used to place restrictions on character-based attributes.

21. String comparisons are made from left to right.

22. Date procedures are often more software-specific than other SQL procedures.

23. SQL allows the use of logical restrictions on its inquiries such as OR, AND, and NOT.

24. ANSI-standard SQL allows the use of special operators in conjunction with the WHERE clause.

25. The conditional LIKE must be used in conjunction with wildcard characters.

26. Most SQL implementations yield case-insensitive searches.

27. Some RDBMSs, such as Microsoft Access, automatically make the necessary conversions to eliminate case sensitivity.

28. The COUNT function is designed to tally the number of non-null "values" of an attribute, and is often used in conjunction with the DISTINCT clause.

29. To join tables, simply enumerate the tables in the FROM clause of the SELECT statement. The DBMS will create a Cartesian product of every table in the FROM clause. To get the correct results, you need to select the rows in which the common attributes do not match.

30. When joining three or more tables, you need to specify a join condition for one pair of tables.