1. Banner and the SQL Select Statement: Part Two (Single Table Selects) Mark Holliday Department of Mathematics and Computer Science Western Carolina University 14 October, 28 October, and 4 November (updated: 4 November 2005)

2. Outline  The Goal  The Concepts A First Example Single Table Selects Joins Multiple Connected Select Statements

3. A First Example  Outline The Relational Model: Single Table Lab 1: TOAD, Schema Browser Some Structured Query Language (SQL) Basics Lab 2: TOAD, SQL Editor

4. Single Table Selects  Outline WHERE clause: single condition, multiple conditions Lab 3: Aliases; Order By; Aggregate Functions Lab 4: Group By; Having Lab 5:

5. WHERE Clause  We might want to keep on specific rows from a table based on a condition => where clause SELECT "column_name" FROM "table_name" WHERE "condition"  We then project onto the columns of interest => select clause

6. WHERE Clause (franz)  This condition can be a simple condition, or it can be a compound condition.  Compound conditions are made up of multiple simple conditions connected by AND or OR.  There is no limit to the number of simple conditions that can be present in a single SQL statement. SELECT "column_name" FROM "table_name" WHERE "simple condition" {[AND|OR] "simple condition"}+

7. WHERE Clause  Each simple condition must evaluate to the value True or the value False.  Operators within a simple condition? arithmetic comparison operators is, is not in, between like

8. Arithmetic Comparison Operators (franz) WHERE age > 18

9. English Query:  Suppose we were going to offer a new scholarship from Ben & Jerry’s Ice Cream Company. The eligible students are listed in the spriden table. Eligible student need to have a first name of ‘Arnold’. We want to find the first and last names of the eligible students.  Solution? A Single Condition Example

10. SELECT spriden_last_name, spriden_first_name FROM spriden WHERE spriden_first name = ‘Arnold’ A Single Condition Example

11. How do we remember the column names in the spriden table? They are in the Columns tab of the Schema Browser  open Schema Brower,  make Saturn the owner,  select the SPRIDEN table,  select the Columns tab (it is the default) A Single Condition Example

12. How do we remember the column names in the spriden table? Shortcut:  in the sql statement in the SQL editor select the table name, spriden,  right-click to open a menu  select the Describe menu item (near the bottom)  the Columns tab from the Schema Browser for that table appears A Single Condition Example

13. Problem: In spriden the spriden_pidm column is not a key => need not determine a unique row Why? PIDM refers to a particular person, but a person may have several spriden rows. SPRIDEN_CHANGE_IND is NULL

14. Why? The information about a person changes (e.g. address) but we want to keep the old information => the person will have multiple spriden rows. SPRIDEN_CHANGE_IND is NULL

15. Question: Of all the spriden rows for a particular person (all have the same PIDM) how do we find the row with the person’s current information? Answer: That row has the null value in the change indicator field, spriden_change_ind SPRIDEN_CHANGE_IND is NULL

16. Question: What is the NULL value? Answer:  Every column has a data type (e.g. INTEGER, VARCHAR)  What if the column entry is currently empty?  We can’t use any value in the data type.  Solution: Use a special value called NULL. SPRIDEN_CHANGE_IND is NULL

17. Question: How do you check for the NULL value? Answer:  Use the IS operator or the IS NOT operator. where spriden_change_ind is null  Can not use the = or <> operators SPRIDEN_CHANGE_IND is NULL

18. Problem: For a Single Condition Example above we really need two conditions spriden_change_ind is null spriden_first_name = ‘Arnold’  and both conditions must be true A Two Condition Example

19. Truth Table for AND logical operator False TrueFalse True Opd1 AND Opd2Opd2Opd1

20. Truth Table for OR logical operator False True False TrueFalseTrue Opd1 OR Opd2Opd2Opd1

21. SELECT spriden_last_name, spriden_first_name FROM spriden WHERE (spriden_change_ind is null) and (spriden_first name = ‘Arnold’) A Two Condition Example

22. SELECT spriden_last_name, spriden_first_name FROM spriden WHERE spriden_change_ind is null and spriden_first name = ‘Arnold’ A Second Equivalent Two Condition Example

23. Suppose we were going to offer a new scholarship from Ben & Jerry’s Ice Cream Company. In order to apply eligible students need to have  a first name of ‘Arnold’ or  or a first name of ‘Arturo’ and  have active records (that is change indicator must be null)  Solution? A Three Condition Example (franz)

24. SELECT spriden_last_name, spriden_first_name FROM spriden WHERE spriden_change_ind is null and (spriden_first name = ‘Arnold’ or spriden_first_name = ‘Arturo’) Note that the first name can be Arnold OR Arturo. But, in either case, the change indicator must be null. A Three Condition Example (franz)

25. SELECT spriden_last_name, spriden_first_name FROM spriden WHERE (spriden_change_ind is null and spriden_first name = ‘Arnold’) or spriden_first_name = ‘Arturo’ How is this query different? The Importance of Parentheses

26. SELECT spriden_last_name, spriden_first_name FROM spriden WHERE (spriden_change_ind is null and spriden_first name = ‘Arnold’) or spriden_first_name = ‘Arturo’ Like the previous query this query includes students who have a first name of ‘Arnold’ and a spriden_change_ind value of null. However this query includes all students who have a first name of ‘Arturo’ even those who have spriden_change_ind not equal to null. The Importance of Parentheses

27. SELECT spriden_last_name, spriden_first_name FROM spriden WHERE spriden_change_ind is null and spriden_first name = ‘Arnold’ or spriden_first_name = ‘Arturo’ To which of the statements before is this one equivalent? The Importance of Parentheses

28. AND is of higher precedence than OR the query is equivalent to SELECT spriden_last_name, spriden_first_name FROM spriden WHERE (spriden_change_ind is null and spriden_first name = ‘Arnold’) or spriden_first_name = ‘Arturo’ Morale: Use parentheses for readability and to avoid surprises The Importance of Parentheses

29. SELECT spriden_last_name, spriden_first_name FROM spriden WHERE spriden_first name = ‘Arnold’ or spriden_first_name = ‘Arturo’ and spriden_change_ind is null To which of the statements before is this one equivalent? The Importance of Parentheses

30. Answer: None! Because AND is higher precedence than OR, the query is equivalent to: SELECT spriden_last_name, spriden_first_name FROM spriden WHERE spriden_first name = ‘Arnold’ or (spriden_first_name = ‘Arturo’ and spriden_change_ind is null) The Importance of Parentheses

31. SELECT spriden_last_name, spriden_first_name FROM spriden WHERE spriden_change_ind is null and (spriden_first name = ‘Arnold’ or ‘Arturo’) What will this query do? A Proposed Query

32. Query will generate an error since  one operand to the OR operator is not a boolean value (that is, True or False)  which one? ‘Arturo’  Morale: SQL is pickier than English sometimes. A Proposed Query

33. IN Operator (franz) SELECT "column_name" FROM "table_name" WHERE "column_name" IN ('value1', 'value2',...)  In SQL, there are two uses of the IN keyword, and this section introduces the one that is related to the WHERE clause.  When used in this context, we know exactly the value of the returned values we want to see for at least one of the columns.

34. IN Operator (franz)  The number of values in the parenthesis can be one or more, with each value separated by comma.  Values can be numerical or characters. If there is only one value inside the parenthesis, this command is equivalent to: WHERE "column_name" = 'value1'  Character values should be enclosed in single quotes.  Numeric values would not be enclosed in quotes.

35. The example below would select valid states codes and descriptions from the valid state table that are either of the values “NC” or “SC”. An Example of the IN Operator (franz)

36. SELECT stvstat_code, stvstat_desc FROM stvstat WHERE stvstat_code IN (‘NC’, ‘SC’) An Example of the IN Operator (cont.) (franz)

37. BETWEEN Operator (franz) SELECT "column_name" FROM "table_name" WHERE "column_name" BETWEEN 'value1‘ AND 'value2' Whereas the IN keyword helps people limit the selection criteria to one or more discrete values, the BETWEEN keyword allows for selecting a range.

38. Perhaps you wanted to know the names of the first 100 names loaded onto the ‘spriden’ table. (As they were loaded, the PIDM was assigned as a sequentially incremented integer.) This example pulls all pidms, last and first names, and change indicators, from spriden for PIDM’s between 0 and 100. An Example of the Between Operator (franz)

39. SELECT spriden_pidm, spriden_last_name, spriden_first_name, spriden_change_ind FROM spriden WHERE spriden_pidm BETWEEN 0 and 100 An Example of the Between Operator (cont.)(franz)

40. LIKE SELECT "column_name" FROM "table_name" WHERE "column_name" LIKE {PATTERN} LIKE is another keyword that is used in the WHERE clause. We previously saw an example where we pulled name information like ‘Er%’ in the first name field. Basically, LIKE allows you to do a search based on a pattern, rather than specifying exactly what is desired (as when using the IN syntax) or spell out a range (as in BETWEEN).

41. The syntax for LIKE is: (franz) LIKE {PATTERN}  where {PATTERN} often consists of wildcards Here are some examples:

42. Examples of the LIKE Operator (franz) 'A_Z': All strings that starts with 'A', contains one other character, and ends with 'Z'. For example, 'ABZ' and 'A2Z' would both satisfy the condition, while 'AKKZ' would not (because there are two characters between A and Z instead of one). 'ABC%': All strings that start with 'ABC'. For example, 'ABCD' and 'ABCABC' would both satisfy the condition. '%XYZ': All strings that end with 'XYZ'. For example, 'WXYZ' and 'ZZXYZ' would both satisfy the condition. '%AN%': All string that contain the pattern 'AN' anywhere. For example, 'LOS ANGELES' and 'SAN FRANCISCO' would both satisfy the condition.

43. A first LIKE Example (franz) SELECT * FROM spriden WHERE spriden_first_name like ‘Er%’ Strings must be in single quotes. Also, please note Banner name fields are CASE sensitive. (Last and first names are mixed case.) This example would retrieve “Ernie Jones” and “Ernestine Smith” but NOT “ERNIE Jones” or “ERNESTINE Smith” (which are capitalized).

44. A Second LIKE Example (franz) SELECT * FROM spriden WHERE spriden_change_ind is null and spriden_last_name like ‘Smith%’

45. Laboratory Three  Objectives: Develop competence with the WHERE clause in single table select statements  Steps First query Second query Third query

46. Laboratory Three First Query:  Find the pidms and area codes of all the people who  have area codes that are 608 or 414.  Hint: use the sprtele table.  Do in two different ways.

47. Laboratory Three First Query Solution (First Way): select sprtele_pidm, sprtele_area_code from sprtele where sprtele_area_code in (‘608’, ‘414’)

48. Laboratory Three First Query Solution (Second Way): select sprtele_pidm, sprtele_area_code from sprtele where (sprtele_area_code = ‘608’ or (sprtele_area_code = ‘414’)

49. Laboratory Three Second Query:  Find the pidms and area codes of all the people who  have area codes that are 608 or 414  and the local phone number ends with a ’2’.  Do in two different ways.

50. Laboratory Three Second Query Solution (First Way): select sprtele_pidm, sprtele_area_code, sprtele_phone_number from sprtele where sprtele_area_code in (‘608’, ‘414’) and sprtele_phone_number like ‘%2’

51. Laboratory Three Second Query Solution (Second Way; First Equivalent): select sprtele_pidm, sprtele_area_code, sprtele_phone_number from sprtele where ((sprtele_area_code =‘608’) or (sprtele_area_code = ‘414’)) and (sprtele_phone_number like ‘%2’)

52. Laboratory Three Second Query Solution (Second Way; Second Equivalent): select sprtele_pidm, sprtele_area_code, sprtele_phone_number from sprtele where (sprtele_area_code =‘608’ or sprtele_area_code = ‘414’) and sprtele_phone_number like ‘%2’

53. Laboratory Three Second Query Solution (Second Way; Third Equivalent): select sprtele_pidm, sprtele_area_code, sprtele_phone_number from sprtele where sprtele_area_code =‘608’ or sprtele_area_code = ‘414’ and sprtele_phone_number like ‘%2’

54. Laboratory Three Is this statement equivalent to the second way? select sprtele_pidm, sprtele_area_code, sprtele_phone_number from sprtele where sprtele_area_code =‘608’ and sprtele_phone_number like ‘%2’ or sprtele_area_code = ‘414’

55. Laboratory Three No. It is equivalent to select sprtele_pidm, sprtele_area_code, sprtele_phone_number from sprtele where (sprtele_area_code =‘608’ and sprtele_phone_number like ‘%2’) or sprtele_area_code = ‘414’

56. Laboratory Three Third Query:  Find the pidms and area codes of all the people who  have area codes that greater than or equal to 600 and less than or equal to 700.

57. Laboratory Three Third Query Solution: select sprtele_pidm, sprtele_area_code, from sprtele where sprtele_area_code between ‘600’ and ‘700’

58. Aliases (franz) There are two types of aliases used most frequently:  Column alias  Table alias

59. COLUMN Alias (franz) SUM(SALES)/12 monthly_sales In this example, the total sales were divided by 12 to derive the monthly sales amount. The alias “monthly_sales” is understandable and could be easily referenced.

60. TABLE Alias (franz)  The table alias is placed directly after the table name in the FROM clause.  This is convenient when you want to obtain information from two separate tables (the technical term is 'perform joins').  The advantage of using a table alias when performing joins is readily apparent when we talk about joins later.

61. TABLE Alias (franz) Before we get into joins, though, let's look at the syntax for both the column and table aliases: SELECT "table_alias"."column_name1" "column_alias" FROM "table_name" "table_alias“

62. Using an example from ‘spriden’, if we were creating a quick ad-hoc query that would only run this one time, to select last names starting with “S”, “J”, or “F”, we might save ourselves some typing time by using the alias syntax as follows: SELECT s.spriden_last_name ln FROM spriden s WHERE ln like ‘S%’ or ln like ‘J%’ or ln like ‘F%’ An Alias Example (franz)

63. ORDER BY Clause (franz) SELECT "column_name" FROM "table_name" [WHERE "condition"] ORDER BY "column_name" [ASC, DESC] The [ ] means that the WHERE statement is optional. However, if a WHERE clause exists, it comes before the ORDER BY clause. ASC means that the results will be shown in ascending order, and DESC means that the results will be shown in descending order. If neither is specified, the default is ASC.

64. ORDER BY Clause (franz) SELECT "column_name" FROM "table_name" [WHERE "condition"] ORDER BY "column_name" [ASC, DESC] It is possible to order by more than one column. In this case, the ORDER BY clause above becomes: ORDER BY "column_name1" [ASC, DESC], "column_name2" [ASC, DESC]

65. AGGREGATE FUNCTIONS (franz) Aggregate functions allow you to create a single value from the rows in a result set. Arithmetic functions:  AVG  COUNT  MAX  MIN  SUM

66. An example aggregate function syntax using the COUNT function is: SELECT COUNT("column_name") FROM "table_name“ COUNT and DISTINCT can be used together in a statement to fetch the number of distinct entries in a table. AGGREGATE FUNCTIONS (franz)

67. For example, if we want to find out the number of distinct address types for Banner, we'd type: SELECT COUNT(DISTINCT stvatyp_code) FROM stvatyp The result would look like this: AGGREGATE FUNCTIONS (franz)

68. Warning! if the SELECT clause uses an aggregate function, then  it must use only aggregate functions  unless the query has a GROUP BY clause  Why? Aggregate function => single value other operands in a SELECT clause (e.g. columns) may have multiple values => conflict AGGREGATE FUNCTIONS

69. Laboratory Four  Objectives: Develop competence with aggregate functions  Steps: First Query Second Query Third Query

70. Laboratory Four First Query:  Find the largest pidm in spriden for someone whose currently active and whose first name is ‘Mark’.  Label that column ‘Largest.’

71. Laboratory Four First Query Solution: select max(spriden_pidm) as Largest from spriden where spriden_change_ind is null and spriden_first_name = ‘Mark’

72. Laboratory Four Second Query:  Find how many telephone numbers have a 919 area code.  Label that column ‘919 Numbers.’  Use the sprtele table.

73. Laboratory Four Second Query Solution: select count(*) as “919 Numbers” from sprtele where sprtele_area_code = ‘919’

74. Laboratory Four Third Query:  Find how many telephone number have a 919 area code.  Label that column ‘919 numbers.’  In the same query, find the smallest pidm of a person with a 919 area code.  Label that column ‘Smallest.’  Hint: use the sprtele table.

75. Laboratory Four Third Query Solution: select count(*) as “919 Numbers”, min(sprtele_pidm) Smallest from sprtele where sprtele_area_code = ‘919’

76. GROUP BY Clause (franz) SELECT "column_name1", SUM("column_name2") FROM "table_name" GROUP BY "column_name1" The GROUP BY keyword is used when we are selecting multiple columns from a table (or tables) and at least one arithmetic operator appears in the SELECT statement. When that happens, we need to GROUP BY all the other selected columns -- i.e., all columns except the one(s) operated on by the arithmetic operator.

77. Task: calculate the number of people in our records – by gender and hair code (franz) SELECT spbpers_sex, spbpers_hair_code, COUNT(*) FROM spbpers GROUP BY spbpers_sex, spbpers_hair_code

78. The HAVING Clause (franz) SELECT "column_name1", AGGREGATE_FNC("column_name2") FROM "table_name" WHERE “conditions” GROUP BY "column_name1" HAVING (arithmetic function condition)

79. The HAVING Clause This is complicated! How do we keep it all straight? Answer: SQL is said to be non-procedural, but  the order of execution of the clauses is procedural  the order of execution of the expressions within a clause (e.g. WHERE and HAVING) is non-procedural

80. The HAVING Clause 5) SELECT "column_name1", AGGREGATE_FNC("column_name2") 1) FROM "table_name" 2) WHERE “conditions” 3) GROUP BY "column_name1" 4) HAVING (arithmetic function condition) Order of execution of the clauses

81. The HAVING Clause  Step 2)The WHERE clause elimination of rows is done on the individual rows BEFORE the GROUP BY and HAVING clauses.  Step 3) The grouping of the remaining rows into groups by the GROUP BY clause is done before the HAVING clause.

82. The HAVING Clause  Step 4) The HAVING clause eliminates groups that do not meet the HAVING conditions.  Step 5) The projection onto columns and application of aggregate functions in the SELECT clause is done last.

83. Task: For each state count the records in the address table where the address type is “MA” (home/permanent mailing). Display the counts only for the states that have ten or more such addresses. SELECT spraddr_stat_code, COUNT(*) FROM spraddr WHERE spraddr_atyp_code = ‘MA’ GROUP BY spraddr_stat_code HAVING COUNT(*) > 9 A HAVING Example (franz)

84. A subset of the result would look something like this: A HAVING Example (cont.) (franz)

85. Laboratory Five  Objectives: Develop competence with the GROUP BY and HAVING clauses  Steps: First Query Second Query

86. Laboratory Five First Query:  For each area code  find the largest phone number

87. Laboratory Five First Query Solution: select sprtele_phone_area, max(sprtele_phone_number) from sprtele group by sprtele_phone_area

88. Laboratory Five Second Query:  Count the number of records in the telephone table for each area code.  However, only consider area codes from 600 through 800 and  Only consider area codes where the number of records is at least five.

89. Laboratory Five Second Query Solution: select sprtele_phone_area, count(*) from sprtele where sprtele_area_code between ‘600’ and ‘800’ group by sprtele_phone_area having count(*) > 5

90. Joins  Outline Why multiple tables? Inner Joins Lab 6: Outer Joins Lab 7:

91. Multiple Connected Select Statements  Outline Set Operators Lab 8: Subqueries  Use directly: FROM clause  Use as a set: new operators  Use as a single value: aggregate functions Lab 9: A Query Development Methodology