28. ________ was adopted as a national standard by ANSI in 1992.
29. SQL is:
30. The condition in a WHERE clause can refer to only one value.
31. The ADD command is used to enter one row of data or to add multiple rows as a result of a query.
32. SQL provides the AS keyword, which can be used to assign meaningful column names to the results of queries using the SQL built-in functions.
33. The SELECT command, with its various clauses, allows users to query the data contained in the tables and ask many different questions or ad hoc queries.
34. A SELECT statement within another SELECT statement and enclosed in square brackets ([...]) is called a subquery.
35. The rows of the result relation produced by a SELECT statement can be sorted, but only by one column.
36. There is an equivalent join expression that can be substituted for all subquery expressions.
37. A dynamic view is one whose contents materialize when referenced.
38. SQL is a programming language.
39. SELECT DISTINCT is used if a user wishes to see duplicate columns in a query.
40. Indexes can usually be created for both primary and secondary keys.
41. Each index consumes extra storage space and also requires overhead maintenance time whenever indexed data change value.
42. The HAVING clause acts like a WHERE clause, but it identifies groups that meet a criterion, rather than rows.
43. SQL is a data sublanguage.
44. The qualifier DISTINCT must be used in an SQL statement when we want to eliminate duplicate rows.
45. DISTINCT and its counterpart, ALL, can be used more than once in a SELECT statement.
46. The result of every SQL query is a table.
47. COUNT(field_name) tallies only those rows that contain a value; it ignores all null values.
48. SUM, AVG, MIN, and MAX can only be used with numeric columns.
49. Most companies keep at least two versions of any database they are using.
50. The format SELECT-FROM-WHERE is the fundamental framework of SQL SELECT statements.