This document discusses basic SQL queries including selecting columns, sorting, filtering with WHERE clauses, combining conditions with AND and OR, aggregate functions like SUM and AVG, removing duplicates with DISTINCT, and grouping with GROUP BY. It includes examples of SQL queries and their corresponding analyses to demonstrate these fundamental SQL features.

1. Part I – simple queries
Database Design and Development: A
Visual Approach © 2006 Prentice Hall
Chapter 9

2. Sky_Member Database
Exhibit 9-1: Sky_Member Database Data Model

3. Creating a Query
1
2
Exhibit 9-2: Creating a Query

4. The Design View
1
2
Exhibit 9-3: The Design View

5. The SQL View
1
2
Exhibit 9-4: Selecting the SQL View for a Query

6. SQL Equivalent of a Query
Exhibit 9-5: The SQL View for a Query

7. SQL Select All Columns and Rows
Exhibit 9-6: Analysis of the Select Statement Retrieving All Columns and Rows

8. Selecting Explicit Columns
Exhibit 9-7: Query with an Explicit Column List

9. SQL: Selecting Explicit Columns
Exhibit 9-8: The Analysis of the Select Statement with an Explicit Column List

10. Sorting
Exhibit 9-9: Designing a Query with Sorting

11. Analysis: Sorting
Exhibit 9-10a: Select Statement with Order by
Clause, BEFORE sorting

12. Analysis: Sorting
Exhibit 9-10b: Select Statement with Order by
Clause

13. Multiple Column Sort
Exhibit 9-11: Design of a Query with Multiple Sort Columns

14. Analysis: Multiple Column Sort
Exhibit 9-12: Analysis of Sorting by Multiple Columns

15. Analysis: Multiple Column Sort
Exhibit 9-12: Analysis of Sorting by Multiple
Columns

16. Conditional Operators
Exhibit 9-13: Conditional Operators

17. SQL: Where Clause
Exhibit 9-14: Entering a Criterion for a Column

18. Analysis: Where Clause Query
Exhibit 9-15: Analysis of Query with a
Where Clause

19. Analysis: Where Clause Query
Exhibit 9-15: Analysis of Query with a
Where Clause

20. Text Column Conditions
Exhibit 9-16: Designing a Query with a Condition
Involving a Text Column

21. Linking Conditions with AND
Conditions: jumps > 10 AND skill = ‘I’
Exhibit 9-18: Multiple Conditions Linked
with an AND

22. Linking Conditions with OR
Conditions: jumps > 10 OR skill = ‘I’
Exhibit 9-19: Multiple Conditions Linked
with an OR

23. Query Using AND
Exhibit 9-20: Combining Two Conditions
with an AND

24. Analysis: Query Using AND
Exhibit 9-21: The Analysis of the Query Using an
AND Relationship

25. Analysis: Query Using AND
Exhibit 9-21: The Analysis of the Query Using an
AND Relationship

26. Analysis: Query Using AND
Exhibit 9-21: The Analysis of the Query Using an
AND Relationship

27. Query Using OR
Exhibit 9-22: Combining Two Conditions
with an OR

28. Analysis: Query Using OR
Exhibit 9-23: The Analysis of the Query Using an
OR Relationship

29. Analysis: Query Using OR
Exhibit 9-23: The Analysis of the Query Using an
OR Relationship

30. Conditions on the Same Column
Exhibit 9-24: Using the AND Operator to Select
Based on a Range of Values

31. Analysis: Conditions on the Same Column
Exhibit 9-25: The Analysis of the Query
Jumps > 10 and Jumps < 20

32. Analysis: Conditions on the Same Column
Exhibit 9-25: The Analysis of the Query
Jumps > 10 and Jumps < 20

33. Analysis: Conditions on the Same Column
Exhibit 9-25: The Analysis of the Query
Jumps > 10 and Jumps < 20

34. Between Operator
Exhibit 9-28: Using the Between Operator

35. Analysis: Between Operator
Exhibit 9-29: Analysis of the Query Using
Between

36. Conditions on Same Column with OR
Exhibit 9-26: Using OR to Enter Multiple
Criteria on the Same Column

37. Combining AND and OR Incorrectly
Exhibit 9-30: Incorrectly Combining AND
and OR

38. SQL: Incorrectly Combining AND and OR
Exhibit 9-31: Analysis of the Query Incorrectly
Combining AND and OR

39. Analysis: Incorrectly Combining AND and OR
Exhibit 9-31: Analysis of the Query Incorrectly
Combining AND and OR

40. Analysis: Incorrectly Combining AND and OR
Exhibit 9-31: Analysis of the Query Incorrectly
Combining AND and OR

41. Correctly Combining AND and OR
Exhibit 9-32: Correctly Combining AND and OR

42. SQL: Correctly Combining AND and OR
Exhibit 9-33: The Analysis of the Query
Correctly Combining AND and OR

43. SQL: Correctly Combining AND and OR
Exhibit 9-33: The Analysis of the Query
Correctly Combining AND and OR

44. SQL: Correctly Combining AND and OR
Exhibit 9-33: The Analysis of the Query
Correctly Combining AND and OR

46. Aggregate Functions
Exhibit 9-34: Commonly Used Aggregate
Functions

47. Summing the Number of Jumps
Aggregate functions result in the display of a single value.
Exhibit 9-35: A Query that Sums the Number of Jumps

48. SQL: Sum Function
Exhibit 9-36: Analysis of the Query that Sums
the Number of Jumps

49. Analysis: Sum Function
Exhibit 9-36: Analysis of the Query that Sums
the Number of Jumps

50. Analysis: Using Where with Sum
Exhibit 9-37: Analysis of the Query that Uses
Sum with Where

51. Analysis: Using Where with Sum
Exhibit 9-37: Analysis of the Query that Uses
Sum with Where

52. Analysis: Using Where with Sum
Exhibit 9-37: Analysis of the Query that Uses
Sum with Where

53. Repeated Values
SELECT skill
FROM sky_member;
If you want to know the possible skills in the Member table,
this query lists them multiple times.
Exhibit 9-38: Selecting Skills

54. Using DISTINCT
SELECT DISTINCT skill
FROM sky_member
Distinct eliminates duplicate rows from the display.
Exhibit 9-39: Selecting Skills Using Distinct

55. Using GROUP BY
SELECT
FROM
GROUP BY
skill, Avg(jumps) AS ‘AverageJumps’
sky_member
skill;
Exhibit 9-41: The Design for the Query
Using Group By

56. Analysis: GROUP BY
Exhibit 9-42: The Analysis for the Query Using
Group By

57. Analysis: GROUP BY
Exhibit 9-42: The Analysis for the Query Using
Group By

58. Analysis: GROUP BY
Exhibit 9-42: The Analysis for the Query Using
Group By

59. Incorrect Use of GROUP BY
SELECT
FROM
skill, Avg(jumps) AS ‘AverageJumps’
sky_member;
GROUP BY must be used, and the same column must be used in the
GROUP BY and the aggregate function.
Exhibit 9-40: Error Generated by missing
GROUP BY specification

60. GROUP BY and HAVING
SELECT skill,
Avg(jumps) AS ‘AverageJumps’
FROM sky_member
GROUP BY skill
HAVING Avg(jumps) < 20
Having eliminates aggregations
that do not meet the conditions.
Exhibit 9-43: The Design for the Query
Using Having

61. Analysis: HAVING Clause
Exhibit 9-44: The Analysis for the Query Using
Having

62. Analysis: HAVING Clause
Exhibit 9-44: The Analysis for the Query Using
Having

63. Analysis: HAVING Clause
Exhibit 9-44: The Analysis for the Query Using
Having

64. HAVING and WHERE
SELECT skill,
Avg(jumps) AS ‘AverageJumps’
FROM sky_member
WHERE equip = ‘Y’
GROUP BY skill
HAVING Avg(jumps) > 10
Exhibit 9-45: Results for the Query Using
Having and Where

65. Analysis: HAVING and WHERE
Exhibit 9-46: The Analysis for the Query Using
Having and Where

66. Analysis: HAVING and WHERE
Exhibit 9-46: The Analysis for the Query Using
Having and Where

67. Analysis: HAVING and WHERE
Exhibit 9-46: The Analysis for the Query Using
Having and Where