1. Database Design Sections 17 & 18 – Concatenations, DISTINCT, DESCRIBE, Logical Operators, Order of Operations, Sorting

2. Marge Hohly2 Concatenation  A concatenation operator: Concatenates columns or charter strings to other columns Is represented by two vertical bars (||) Creates a resultant column that is a character expression

3. Marge Hohly3 Practice  SELECT last_name ||', '|| first_name FROM employees;  Using the DJ on Demand EVENT table, create and display : "On date, the event was name“  Run the command again using an alias Events for the column heading  Create SQL to get the phase like “King earns $24000” from the employees table  SELECT doesn’t change data

4. Marge Hohly4 Practice database UCLA  CREATE table UCLA (id number, name varchar2(20));  DESC ucla;  INSERT INTO ucla values(1,'Joe');  values(2,‘Mary');  SELECT * FROM ucla;  We can use the ucla table for practice during lecture

5. Marge Hohly5 Using Literal Character Strings  A literal is a character, a number, or a date included in the SELECT list.  Date and character literal values must be enclosed within single quotation marks.  Each character string is output once for each row returned.

6. Marge Hohly6 Using Literals  SELECT id, 'hello‘ FROM ucla; hello is a literal This inserts values in a column of the UCLA table with the value ‘hello’ Try it. Try this: SELECT id, 15 FROM ucla

7. Marge Hohly7 DISTINCT: Eliminating duplicate rows  The default display of queries is all rows, including duplicate rows.  Use the DISTINCT keyword in the SELECT clause to eliminate duplicate rows.  DISTINCT must appear just after the SELECT keyword.

8. Marge Hohly8 DISTINCT practice  SELECT job_id FROM employees; Note the large number of rows returned Revise using DISTINCT  SELECT DISTINCT job_id FROM employees;  When DISTINCT is after the SELECT it applies to all other fields in the SELECT  SELECT DISTINCT job_id, salary FROM employees;

9. Marge Hohly9 Limiting rows  SELECT*|{[DISTINCT] column|expression [alias],...} FROM table [WHEREcondition(s)];  Example: SELECT DISTINCT year AS “Year” FROM d_cds WHERE year < 2000;

10. Marge Hohly10 Practice 17.1.10 2.Each statement below has errors. Correct the errors and execute the query in HTML DB. a.SELECT first name FROM f_staffs; b.SELECT first_name |" " | last_name AS "DJs on Demand Clients“ FROM d_clients; c.SELECT DISCTINCT f_order_lines FROM quantity; d.SELECT order number FROM f_orders;

11. Marge Hohly11 Using DESCRIBE (DESC)  Use the DESCRIBE command to display the structure of a table. DESC[RIBE] tablename

12. Marge Hohly12 Practice 17.1.11 4.Which of the following is TRUE about the following query? SELECT first_name, DISTINCT birthdate FROM f_staffs; a.Only two rows will be returned. b.Four rows will be returned. c.Only Fred 05-JAN-88 and Lizzie 10-NOV-87 will be returned. d.No rows will be returned.

13. Marge Hohly13 Practice 17.2.4 1.True/False -- The following SELECT statement executes successfully: SELECT last_name, job_id, salary AS Sal FROM employees; 2.True/False -- The following SELECT statement executes successfully: SELECT * FROM job_grades; 3.There are four coding errors in this statement. Can you identify them? SELECT employee_id, last_name sal x 12 ANNUAL SALARY FROM employees; 4.In the arithmetic expression salary*12 - 400, which operation will be evaluated first?

14. Marge Hohly14 Practice 17.2.5 5.Which of the following can be used in the SELECT statement to return all columns of data in the Global Fast Foods f_staffs table? a. column names b. * c.DISTINCT id d.both a and b 5.Using SQL to choose the columns in a table uses which capability? a.selection b.projection c.partitioning d.join 6.SELECT department_id, first_name, last_name AS "Employee". The column heading in the query result will appear as: a.EMPLOYEE b.employee c.Employee d."Employee:

15. Marge Hohly15 Practice 17.2.6 8.Which statement below will return a list of employees in the following format? Mr./Ms. Steven King is an employee of our company. a.SELECT "Mr./Ms."||first_name||' '||last_name 'is an employee of our company.' AS "Employees“ FROM employees; b.SELECT 'Mr./Ms. 'first_name,last_name ||' '||'is an employee of our company.' FROM employees; c.SELECT 'Mr./Ms. '||first_name||' '||last_name ||' '||'is an employee of our company.' AS "Employees“ FROM employees d.SELECT Mr./Ms. ||first_name||' '||last_name ||' '||"is an employee of our company." AS "Employees“ FROM employees 9.Which expression below will produce the largest value? a.SELECT salary*6 + 100 b.SELECT salary* (6 + 100) c.SELECT 6(salary+ 100) d.SELECT salary+6*100

16. Marge Hohly16 Practice 17.2.7 10.Which is true about SQL statements? a.SQL statements are case-sensitive b.SQL clauses should not be written on separate lines. c.Keywords cannot be abbreviated or split across lines. d.SQL keywords are typically entered in lowercase; all other words in uppercase. 11.Which query will return three columns each with UPPERCASE column headings? a.SELECT "Department_id", "Last_name", "First_name“ FROM employees; a.SELECT DEPARTMENT_ID, LAST_NAME, FIRST_NAME FROM employees; a.SELECT department_id, last_name, first_name AS UPPER CASE FROM employees a.SELECT department_id, last_name, first_name FROM employees;

17. Marge Hohly17 Practice 17.2.8 12.Which statement below will likely fail? a.SELCT * FROM employees; b.Select * FROM employees; c.SELECT * FROM EMPLOYEES; d.SelecT* FROM employees; 13.You are now ready to take Quiz #7

18. Marge Hohly18 Limiting Rows with WHERE  The WHERE clause can compare values in columns, literal values, arithmetic expressions, or functions. It consists of three elements: Column name Comparison condition Expressions, constant, or list of values

19. Marge Hohly19 WHERE clause  The WHERE clause follows the FROM clause in a SQL statement.  An alias cannot be used in the WHERE clause!  Example: SELECT last_name, first_name, department_id FROM employees WHERE department_id = 50;

20. Marge Hohly20 Comparison Operators  The symbols != and ^= can also represent the not equal to condition. OperatorMeaning = Equal to > Greater than >= Greater than or equal to < Less than <= Less than or equal to <> Not equal to

21. Marge Hohly21 WHERE clauses  Using comparison operators SELECT last_name,first_name,department_id FROM employees WHERE department_id >= 60; SELECT last_name,first_name,department_id FROM employees WHERE department_id <> 60; Write a SELECT statement to produce the following results: "The song title is "Another one bites the dust. Where ‘Another one bites the dust’ is the title of a song. Remember Oracle SQL is case sensitive

22. Marge Hohly22 BETWEEN... AND  BETWEEN...AND operator is used to select and display rows based on a range of values.  BETWEEN... AND are inclusive SELECT last_name,first_name,department_id FROM employees WHERE department_id BETWEEN 60 AND 90; SELECT last_name,first_name,department_id FROM employees WHERE department_id NOT BETWEEN 60 AND 90; SELECT title, year FROM d_cds WHERE year BETWEEN '1999' AND '2001';

23. Marge Hohly23 More Complex WHERE clause  Example: "I would like to know Global Fast Foods employees whose manager ID is 19 and earn a salary less than $12.00 per hour. SELECT * FROM f_staffs WHERE manager_id = 19 and salary <12.00;

24. Marge Hohly24 WHERE clause using LIKE  LIKE condition allows you to select rows that match either literal characters or number patterns.  % and underscore (_ ) are wildcard characters, used to construct a search string. % symbol used to represent any sequence of zero or more characters. Underscore (_ ) symbol used to represent a single character.

25. Marge Hohly25 LIKE examples  SELECT last_name,first_name,department_id FROM employees WHERE last_name LIKE 'A%';  SELECT last_name,first_name,department_id FROM employees WHERE last_name LIKE '%s‘;  SELECT last_name,first_name,department_id FROM employees WHERE last_name LIKE '%s%‘;  SELECT last_name,first_name,department_id FROM employees WHERE last_name LIKE ‘_ _ _ _ _s%‘ Using 5 underscores

26. Marge Hohly26 Using IS NULL, IS NOT NULL  NULL is unavailable, unassigned, unknown, or inapplicable. No presence of data.  NOT NULL test for presence of data in column/field.  Examples: SELECT last_name,first_name,department_id, commission_pct FROM employees WHERE commission_pct is NULL; SELECT last_name,first_name,department_id, commission_pct FROM employees WHERE commission_pct is NOT NULL;

27. Marge Hohly27 17.5.11 & 17.5.12 2.Display the location type and comments for all DJs on Demand venues that are Private Home. 5.Who are the partners of DJs on Demand who do not get an authorized expense amount?

28. Marge Hohly28 IN is like OR’s  IN is like a string of OR clauses.  Example: SELECT last_name,first_name,department_id FROM employees WHERE department_id IN(50, 60, 90);

29. Marge Hohly29 Logical Comparisons  A logical condition combines the results of two or more conditions to produce a single result. A row is returned ONLY IF the overall result of the condition is true. AND – Returns TRUE if both conditions are true. OR – Returns TRUE if either conditions are true. NOT – Returns TRUE if the condition is false.

30. Marge Hohly30 Precedence using AND & OR  Evaluate these two examples. What is the difference? SELECT last_name, job_id, salary FROM employees WHERE job_id = ‘SA_REP’ OR job_id=‘AD_PRES’ AND salary>15000; SELECT last_name, job_id, salary FROM employees WHERE (job_id = ‘SA_REP’ OR job_id=‘AD_PRES’) AND salary>15000; AND before OR

31. Marge Hohly31 Logical Comparisons  Logical conditions (a few examples) SELECT last_name, job_id, department_id FROM employees WHERE job_id = ‘SA_REP’ OR department_id = 10; SELECT last_name, job_id, SALARY FROM employees WHERE job_id = ‘SA_REP’ AND salary > 15000;  Can you explain what rows are to be returned in each?

32. Marge Hohly32 Logical operator  Write a select statement to find an address in the DJs on Demand database d_venues table that has the word "Primrose" in the description.  SELECT address FROM d_venues WHERE address LIKE '%Primrose%‘;  Variations: …WHERE cd_id NOT IN(105, 206, 332); …WHERE cd_id != 105 and cd_id != 206 and cd_id!= 332;

33. Marge Hohly33 Examples:  Below are phrases and conditions in which they would not be true  employee_id = 100 AND last_name LIKE 'S%' Ms. Smith whose employee_id is 50 Employee_id 100 whose last name is King  department = 10 AND employee_id = 100; Employee_id 100 is in department 20 Employee_id 50 is in department 10

34. Marge Hohly34 Complex AND and OR clause  Take an arc #id ID = A ID = B ID = C

35. Marge Hohly35 Complex AND and OR clause  Example Table: IDABC PKFk1Fk2Fk3 *OOO

36. Marge Hohly36 Complex AND and OR clause  WHERE clause example for ARC: WHERE ((A is NOT NULL and B is NULL and C is NULL) OR (A is NULL and B is NOT NULL and C is NULL) OR (A is NULL and B is NULL and C is NOT NULL)) /*--- comment ---*/ Precedence is AND before OR

37. Marge Hohly37 Rules of Precedence  The rules of precedence determine the order in which expressions are evaluated and calculated. The table lists the default order, which can overridden by using parentheses. OrderOperator 1 Arithmetic operations 2 Concatenation operators 3 Comparison conditions 4 IN [NOT] NULL, LIKE, [NOT] IN 5 [NOT] BETWEEN 6 NOT logical operator 7 AND logical operator 8 OR logical operator

38. Marge Hohly38 Order of Operations Examples  What order will these process in?  SELECT last_name, specialty, auth_expense_amt FROM d_partners WHERE specialty ='All Types‘ OR specialty IS NULL AND auth_expense_amt = 300000;  SELECT last_name, specialty, auth_expense_amt FROM d_partners WHERE (specialty ='All Types‘ OR specialty IS NULL) AND auth_expense_amt = 300000;

39. Marge Hohly39 Examples 18.1.8 & 18.1.9 3.“I need to know who the Global Fast Foods employees are that make more than $6.50/hour and their position is not Order Taker.“ 8.What's my email address? Because I have been working for Oracle since the beginning of 1996, I make more than $9000 per month. Because I make so much money, I don't get a commission.

40. Marge Hohly40 Examples: AND and OR conditions  What are the titles of the jobs whose minimum salary is 4000 and whose maximum salary is 9000?  Try this with OR and then AND  Rewritten query including the salary columns to verify that both conditions are met:  Note: you might want to review the jobs table fields/columns etc.

41. Marge Hohly41 Sorting rows  ORDER BY Information sorted by the column referenced. ORDER BY clause follows the FROM clause and is at the end of the SELECT statement. ORDER BY clause sorts in ascending order by default. Only limit to how many columns can be added to the ORDER BY clause is the number of columns in the table.

42. Marge Hohly42 ORDER BY  Example of single value sort SELECT department_id, job_id, last_name, salary FROM employees ORDER BY department_id desc;

43. Marge Hohly43 ORDER BY multiple values  SELECT department_id, job_id, last_name, salary FROM employees ORDER BY department_id, job_id, salary;  SELECT department_id, job_id, last_name, salary FROM employees ORDER BY department_id, job_id desc, salary;  SELECT department_id, job_id, last_name, salary FROM employees ORDER BY 3; The 3 is field from SELECT  SELECT department_id, job_id, last_name, salary FROM employees ORDER BY 2, last_name;

44. Marge Hohly44 Sort order  The default sort order is ascending. Numeric values are displayed lowest to highest. Date values are displayed with the earliest value first. Character values are displayed in alphabetical order. Null values are displayed last in ascending order and first in descending order.

45. Marge Hohly45 ORDER BY multiple values  Place the following hire dates in descending order: 22-MAY-85, null, 10-JAN-04, 17-NOV-55, 21-DEC-98  Write a query to find the answer, using the employees table and hire_date column

46. Marge Hohly46 Order of execution in a SELECT statement  The order of execution of a SELECT statement is as follows: FROM clause -- locates the table that contains the data WHERE clause -- restricts the rows to be returned SELECT clause -- selects from the reduced data set the columns requested ORDER BY -- orders the results set

47. Marge Hohly47 Example  SELECT employee_id, first_name FROM employees WHERE employee_id < 105 ORDER BY last_name;  What order does this execute in?

48. Marge Hohly48 11.1.7 & 11.1.8 2.Create a query that will return all the DJ on Demand CD titles ordered by year with titles in alphabetical order by year. 5.Write a SQL statement using the employees table and the ORDER BY clause that could retrieve the information in the following table. Return only those employees with employee_id<125.

49. Marge Hohly49 Function classification  Single-row and multi-row functions Single-row functions operate on a single row and return only one result per row. Multiple-row functions can manipulate groups of rows to give one result per group of rows.  This section provides a brief overview of this topic. It is covered in depth in the next section.

50. Marge Hohly50 SQL Single row functions  Character Converting character values from uppercase to lowercase  Number rounding off Manipulate output for groups of rows by finding an average or sum for several rows  Date Format dates and numbers for display  Conversion Convert column data types such as converting a character string to a number or date  General

51. Marge Hohly51 Single-row functions  They can be used in SELECT, WHERE, and ORDER BY clauses.  They return ONE result per row.  They can return a data value of a different type.  They can possibly expect one or more arguments or values sent to them.  They act on each row returned in the query.

52. Marge Hohly52 Examples  SELECT 'The most popular song in our collection is ' || UPPER(title)AS "Most Requested” FROM d_songs WHERE id = 47;  SELECT CONCAT(title, year) FROM d_cds;

53. Marge Hohly53 Examples  Use ‘ single quote when referring to data in a database  Use “ “ for text as an alias if text has space or specific case etc.  In an ORDER BY clause you can use an alias, expression, number, field names SELECT department_id, job_id AS job, last_name, salary*12 FROM employees ORDER BY job; SELECT department_id, job_id AS job, last_name, salary*12 FROM employees ORDER BY salary*12; SELECT department_id, job_id AS job, last_name, salary*12 FROM employees ORDER BY 3;

54. Marge Hohly54 Examples  Fields used in ORDER BY don’t have to be used in SELECT clause  SELECT last_name FROM employees WHERE salary > 4000 ORDER BY job_id;  In development you might want to include the ORDER BY field in SELECT to verify that your getting the correct results, then remove the field.

55. Marge Hohly55 Single-row function example  The single-row function is done for every row  What would be returned from this statement? SELECT last_name || ' ' || first_name, salary,round(salary,-3) FROM employees WHERE salary>400;