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Database Design

Database Design. Sections 12 & 15 - Introduction to Application Express (APEX) SQL editor, Introduction to SQL statements. Using APEX SQL editor. You may either type the command into the SQL editor or use the cut and paste option

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Database Design

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  1. Database Design Sections 12 & 15- Introduction to Application Express (APEX) SQL editor, Introduction to SQL statements

  2. Using APEX SQL editor • You may either type the command into the SQL editor or use the cut and paste option • If you are going to cut/paste the command copy the command from the word or PowerPoint document into NotePad. This will drop out hidden characters. • You may need to do some editing to remove extra characters, or replace incorrect characters. • Next copy the command from the NotePad into the editor Marge Hohly

  3. Enter SQL command Marge Hohly

  4. Display the Table structure • Enter the following command: • DESCRIBE music; • The structure of the table should be shown. • Results on next slide Marge Hohly

  5. Music Table Structure Marge Hohly

  6. Select command structure • SELECT field1, field2, field3FROM table_nameWHERE condition; • Try the following commandSELECT employee_id, first_name, last_name, department_idFROM employees; • SELECT employee_id, first_name, last_name, department_idFROM employeesWHERE department_id = 90; Marge Hohly

  7. Resulting Screen Marge Hohly

  8. SQL DESCRIBE • DESCRIBE <table name>; • DESCRIBE employees;Try the last statement. Marge Hohly

  9. Inserting Data • INSERT INTO tablename (column1, column2,....)VALUES(value1,value2,...); • Remember character data needs to be enclosed in single quotes. Marge Hohly

  10. Insert Data • Note the data types for each column • Inserting data into the table. • Since the table is empty all fields need to be populated, so column names can be omitted • INSERT INTO musicVALUES (10,'Marge Hohly','Folk'); • This will insert one record into the table • Next display the contents of the table to view the data • SELECT *FROM music; Marge Hohly

  11. Insert Data into table • INSERT INTO <table name>VALUES (value 1, value 2, value 3, etc); • INSERT INTO musicVALUES (10,'Marge Hohly','Folk'); Marge Hohly

  12. Typical error messages • The following statement has a spelling error: • SELCT *FROM employees;The error message is:       ORA-00900: invalid SQL statement • The following statement incorrectly names the table employee instead of employees: • SELECT *FROM employee;The error message is:       ORA-00942: table or view does not exist • Run the correct statement. Marge Hohly

  13. Subset of data WHERE clause • SELECT <column name 1, column name 2, etc.> FROM <table name>WHERE <condition>; • SELECT first_name, last_name, salaryFROM employeesWHERE salary > 5000; Marge Hohly

  14. ALTER table structure • ALTER TABLE <table name>ADD (<new_column_name> <data type>); • Try to modify the structure of the MUSIC table • Add a column (which you will misspell) COUNTRI instead of COUNTRY). • ALTER TABLE my_musicADD (countri VARCHAR2(20)); Marge Hohly

  15. Deleting a column from a table • ALTER TABLE <table name>DROP COLUMN <column_name>; • Now delete the column (COUNTRI) you just added. Marge Hohly

  16. Deleting a row • DELETE from <table name>WHERE <column_name> = 'some value' ; • DELETE from musicWHERE musicid = 10; • DELETE from musicWHERE type = ‘Folk’; Marge Hohly

  17. Database Facts • Currently 20% of the world's data resides in relational RDBMSs. • In the next two years, databases are expected to grow larger than 100 terabytes. A database this big would be able to store 100,000 copies of the Encyclopedia Britannica or 200,000 hours of music or about 10 billion web pages. • The top 10 world's largest databases using the Oracle RDBMS are: • France Telecom, 29.2TB -- a communications company (a TB is a terabyte equivalent to 1,000 gigabytes) • Amazon.com with, 13 TB -- selling books and merchandise • The Claria Corporation,12TB -- Internet behavioral marketing company tracking Internet user behavior Marge Hohly

  18. Oracle Facts • One of Oracles first customers was the CIA, for which they created a relational database management system. • Much of Oracles early success was owed to picking up IBM as a major customer. • 2nd half of the ‘90s was spend retooling Oracle products in line with that online strategy (the internet) • Ellison said in 1998: “If the internet turns out not to be the future of computing, we’re toast. But if it is, we’re golden.” • Oracle was the first enterprise software to fully embrace the Java Programming language back in 1998. • Oracle has purchased 57 different companies in the last 5 years. • The buying frenzy was launched with the $10.3 billion acquisition of PeopleSoft in 2005, which put Oracle squarely in the ERP software fray. Marge Hohly

  19. Oracle Facts • The latest mega-purchase: Sun Microsystems, a $7.4 billion acquisition due to close this year if regulators don't object. • Oracle today now has 345,000 customers worldwide. • Oracle employs more than 73,201 people around the globe. • Some of the top 10 world’s largest databases using Oracle RDBMS are: • France Telecom, 29.2 TB – a communications company (a TB is a terebyte equivalent to 1,000 gigabytes) • Amazon.com with, 13TB – selling books and merchandise • The Clarian Corporation, 13TB – Internet behavioral marketing company tracking Internet user behavior Marge Hohly

  20. Application Express SQL editor • The SQL course will use the three following sets of database tables for examples and practice exercises. • Oracle tables: COUNTRIES, REGIONS, DEPARTMENTS, EMPLOYEES, JOBS, JOB_HISTORY AND JOB_GRADES • DJs on Demand database tables: D_CDS, D_PACKAGES, D_TYPES, D_THEMES, D_CLIENTS, D_VENUES, D_SONGS, D_TRACK_LISTINGS, D_PARTNERS, D_EVENTS, D_PLAY_LIST_ITEMS, D_JOB_ASSIGNMENTS • Global Fast Foods database tables: F_CUSTOMERS, F_REGULAR_MENUS, F_PROMOTIONAL_MENUS, F_SHIFTS, F_STAFFS, F_FOOD_ITEMS, F_ORDERS, F_ORDER_LINES, F_SHIFT_ASSIGNMENTS • Print out these tables for your reference when using the Application Express editor • These tables are available on the Student Resource web page for this class Marge Hohly

  21. Review the tables • There are six properties of tables in a relational database: • Property 1: Entries in columns are single-valued. • Property 2: Entries in columns are of the same kind. • Property 3: Each row is unique. • Property 4: Sequence of columns is insignificant. • Property 5: Sequence of rows is insignificant. • Property 6: Each column has a unique name. Marge Hohly

  22. Categories of SQL Statements • Data manipulation language (DML) statements • Begin with INSERT, UPDATE, DELETE, or MERGE • Used to modify the table by entering new rows, changing existing rows, or removing existing rows. • Data definition language (DDL) statements set up, change, and remove data structures from the database. • The keywords CREATE, ALTER, DROP, RENAME, and TRUNCATE begin DDL statements. • Transaction control (TCL) statements are used to manage the changes made by DML statements. • Changes to the data are executed using COMMIT, ROLLBACK, and SAVEPOINT. TCL changes can be grouped together into logical transactions. • Data control language (DCL) • keywords GRANT and REVOKE are used to give or remove access rights to the database and the structures within it. Marge Hohly

  23. Questions • The Fast Foods database consists of how many tables? ____ tables • How is the F_SHIFTS table related to the F_STAFFS table? • What are the names of the columns in the F_CUSTOMERS table? • How many rows of data have been entered in the F_PROMOTIONAL_MENUS table? • In the F_FOOD_ITEMS table, column _________ is a foreign-key column. What table and column is this key referencing? • List the primary key to foreign key relationships required to go from the F_SHIFTS table to the F_REGULAR_MENUS table. • Which table(s) contain null values? Marge Hohly

  24. KEYWORD, CLAUSE, STATEMENT • Throughout this course, the words keyword, clause, and statement are used as follows: • A keyword refers to an individual SQL element. For example, SELECT and FROM are keywords. • A clause is a part of a SQL statement. SELECT employee_id, last_name, .... is a clause. • A statement is a combination of two or more clauses.SELECT *FROM employees; is a SQL statement. Marge Hohly

  25. Selection vs. Projection • SELECT salaryFROM employeesWHERE last_name like ‘Smith’; • Selection (row) Projection (column) Marge Hohly

  26. Join Marge Hohly

  27. SELECT statement • SELECT statements can provide the same information depending on how they are written • Example: • SELECT *FROM d_songs; • SELECT id, title, duration, artist, type_codeFROM d_songs; Marge Hohly

  28. SELECTION • SELECT *FROM employeesWHERE department_id = 60; • SELECT * FROM employeesWHERE salary > 10000; Marge Hohly

  29. Projections • A subset of columns • SELECT first_name, last_name, salaryFROM employees; • SELECT id, title, artistFROM d_songs; Marge Hohly

  30. Arithmetic Expressions • Create expressions with number and date data by using arithmetic operators. Marge Hohly

  31. Operator Precedence • Operator Precedence • Multiplication and division take priority over addition and subtraction. • Operators of the same priority are evaluated from left to right. • Parentheses are used to force prioritized evaluation and to clarify statements. • Remember: Please excuse my dear aunt Sally Marge Hohly

  32. Rewrite in order of precedence • You want to calculate the annual salary if the employee received $100 raise each month • Revise the following statement in the correct order of precedence to get the desired results • Run each example in the editor • SELECT last_name, salary, 12*salary+100FROM employees; Marge Hohly

  33. What is null? • If a row lacks the data value for a particular column, that value is said to be null, or to contain a null. A null is a value that is unavailable, unassigned, unknown, or inapplicable. • A null is not the same as zero. Zero is a number. • A null is not a space. Space is a character. Marge Hohly

  34. Null Values in Arithmetic Expressions • SELECT last_name, salary, commission_pct, salary*commission_pctFROM employees; Marge Hohly

  35. Practice • SELECT *FROM d_songs; • SELECT id, title, duration, artist, type_codeFROM d_songs; • SELECT id, title, artist, FROM d_songs; • SELECT last_name, salary, salary – 300FROM employees; • SELECT last_name, salary, salary * 1.05FROM employees; Marge Hohly

  36. Column Alias • Renames a column heading • Is useful in naming columns of derived values • Immediately follow the column name • Uses optional AS keyword between the column name and alias • Required double quotation marks if it contains spaces or special characters or is case sensitive Marge Hohly

  37. Using Aliases • SELECT last_name name, salary AS Salary, salary*12 “Annual Salary”FROM employees; Marge Hohly

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