Database Design Sections 13 & 16 - Introduction to HTML DB SQL editor, Introduction to SQL statements

Marge Hohly2 Using HTML_DB SQL editor  Reference Lab #6 problem 1  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 document into NotePad. This will drop out hidden characters.  Next copy the command from the NotePad into the editor

Marge Hohly3 Enter SQL command

Marge Hohly4 Display the Table structure  Enter the following command: DESCRIBE MUSIC;  The structure of the table should be shown.  Results on next slide

Marge Hohly5 Music Table Structure

Marge Hohly6 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

Marge Hohly7 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 omited  INSERT INTO music VALUES (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 Hohly8 Resulting Screen

Marge Hohly9 Inserting Data  INSERT INTO tablename (column1, column2,....) VALUES(value1,value2,...);  Remember character data needs to be enclosed in single quotes.

Marge Hohly10 SQL DESCRIBE  DESCRIBE ;  DESCRIBE employees; Try the last statement.

Marge Hohly11 Subset of data WHERE clause  SELECT FROM WHERE ;  SELECT first_name, last_name, salary FROM employees WHERE salary > 5000;

Marge Hohly12 Insert Data into table  INSERT INTO VALUES (value 1, value 2, value 3, etc);  INSERT INTO music VALUES (10,'Marge Hohly','Folk');

Marge Hohly13 ALTER table structure  ALTER TABLE ADD ( );  Try to modify the structure of the MUSIC table  Add a column (which you will misspell) COUNTRI instead of COUNTRY).

Marge Hohly14 Deleting a column from a table  ALTER TABLE DROP COLUMN ;  Now delete the column (COUNTRI) you just added.

Marge Hohly15 Deleting a row  DELETE from WHERE = 'some value' ;  DELETE from music WHERE musicid = 10;  DELETE from music WHERE type = ‘Folk’;

Marge Hohly16 Database Facts  Currently 20% of the world's data resides in relational DBMSs. 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 DBMS 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 Hohly17 HTML DB 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 HTML DB editor  These tables are available on the Student Resource web page for this class

Marge Hohly18 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 Hohly19 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 Questions 1.The Fast Foods database consists of how many tables? ____ tables 2.How is the F_SHIFTS table related to the F_STAFFS table? 3.What are the names of the columns in the F_CUSTOMERS table? 4.How many rows of data have been entered in the F_PROMOTIONAL_MENUS table? 5.In the F_FOOD_ITEMS table, column _________ is a foreign-key column. What table and column is this key referencing? 6.List the primary key to foreign key relationships required to go from the F_SHIFTS table to the F_REGULAR_MENUS table. 7.Which table(s) contain null values?

Marge Hohly21 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 Hohly22 Selection vs. Projection  SELECT salary FROM employees WHERE last_name like ‘Smith’;  Selection (row) Projection (column) IDFirst_nameLast_namesalary 10JohnDoe JaneJones SylviaSmith HaiNguyen6000

Marge Hohly23 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 isa 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 Hohly24 Arithmetic Expressions  Create expressions with number and date data by using arithmetic operators. OperatorDescription +Add -Subtract *Multiply /Divide

Marge Hohly25 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 Hohly26 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+100 FROM employees;

Marge Hohly27 Null Values in Arithmetic Expressions  SELECT last_name, salary, commission_pct, salary*commission_pct FROM employees; SALARYCOMMISSION_PCTSALARY*COMMISSION_PCT 2500(null) (null)

Marge Hohly28 Practice  SELECT * FROM d_songs;  SELECT id, title, duration, artist, type_code FROM d_songs;  SELECT id, title, artist, FROM d_songs;  SELECT last_name, salary, salary – 300 FROM employees;  SELECT last_name, salary, salary * 1.05 FROM employees;

Marge Hohly29 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 Hohly30 Using Aliases  SELECT last_name name, salary AS Salary, salary*12 “Annual Salary” FROM employees; NAMESALARYAnnual Salary Whalen Hartstein Fay