Ch. 6 T/F – Flashcards

43) SQL is both an American and international standard for database access.

44) SQL has been implemented only in the mainframe and midrange environments.

45) SQL originated from a project called System-S.

46) One of the original purposes of the SQL standard was to provide a vehicle for portability of database definition and application modules between conforming DBMSs.

47) A major benefit of SQL as a standard is reduced training costs.

48) Implementation of a standard can never stifle creativity and innovation.

49) Applications can be moved from one machine to another when each machine uses SQL.

50) A catalog is the structure that contains object descriptions created by a user.

51) Some DBMS can handle graphic data types as well as text and numbers.

52) DCL is used to update the database with new records.

53) A database table is defined using the data definition language (DDL).

54) A database is maintained and queried using the data mapping language (DML).

55) The CREATE SCHEMA DDL command is used to create a table.

56) When creating tables, it's important to decide which columns will allow null values before the table is created.

57) When creating a table, it is not important to consider foreign key—primary key mates.

58) A referential integrity constraint specifies that the existence of an attribute in one table depends upon the existence of a foreign key in the same or another table.

59) The DELETE TABLE DDL command is used to remove a table from the database.

60) The ALTER TABLE command is used to change a table definition.

61) The SQL command used to populate tables is the INSERT command.

62) An insert command does not need to have the fields listed.

insert into budget values 121,222,111;

64) The DROP command deletes rows from a table individually or in groups.

65) In order to update data in SQL, one must inform the DBMS which relation, columns, and rows are involved.

66) Indexes generally slow down access speed in most RDMS.

67) The WHERE clause includes the conditions for row selection within a single table or view and the conditions between tables or views for joining.

68) Expressions are mathematical manipulations of data in a table that may be included as part of the SELECT statement.

69) Count(*) tallies only those rows that contain a value, while Count counts all rows.

70) The asterisk (*) wildcard designator can be used to select all fields from a table as well as in WHERE clauses when an exact match is not possible.

71) The comparison operators = and != are used to establish a range of values.

72) If multiple Boolean operators are used in an SQL statement, NOT is evaluated first, then AND, then OR.

73) The following two SQL statements will produce the same results. Select last_name, first_name from customer where credit_limit > 99 and credit_limit < 10001; Select last_name, first_name from customer where credit_limit between 100 and 10000;

74) Adding the DISTINCT keyword to a query eliminates duplicates.

75) The following two SQL statements will produce different results. Select last_name, first_name from customer where state = 'MA' or state = 'NY' or state = 'NJ' or state = 'NH' or state = 'CT'; Select last_name, first_name from customer where state in ('MA','NY','NJ','NH','CT');

76) The ORDER BY clause sorts the final results rows in ascending or descending order.

77) A single value returned from an SQL query that includes an aggregate function is called a vector aggregate.

78) When a GROUP BY clause is included in an SQL statement, only those columns with a single value for each group can be included.

79) The HAVING clause and the WHERE clause perform the same operation.

80) The following query totals sales for each salesperson. Select salesperson_id, sum(sales) from salesperson group by salesperson_id;

81) The following query totals sales in state= 'MA' for each salesperson. Select salesperson_id, sum(sales) from salesperson group by salesperson_id having state = 'MA';

82) The ORDER BY clause is the first statement processed in an SQL command.

83) The WHERE clause is always processed before the GROUP BY clause when both occur in a SELECT statement.

84) The FROM clause is the first statement processed in an SQL command.

85) The content of dynamic views is generated when they are referenced.

86) Materialized views are stored on disk and are never refreshed.

87) The views are created by executing a CREATE VIEW SQL command.

88) When the SELECT clause in the create view statement contains the keyword DISTINCT, the view can be used to update data.