1. 1 DBS201: Introduction to Structure Query Language (SQL) Lecture 1

2. 2 Agenda The basic commands and functions of SQL How to use SQL to query a database to extract useful information

3. 3 Introduction to SQL SQL: Structured Query Language Designed specifically for communicating with databases SQL functions fit into two broad categories: Data definition language Data manipulation language

4. 4 Introduction to SQL ( continued ) Data definition language SQL includes commands to create Database objects such as tables, indexes, and views Commands to define access rights to those database objects Data manipulation language Includes commands to insert, update, delete, and retrieve data within the database tables

5. 5 Introduction to SQL ( continued ) SQL is relatively easy to learn Basic command set has a vocabulary of less than 100 words Sample vocabulary: CREATE COLLECTION CREATE TABLE CREATE VIEW

6. 6 Introduction to SQL ( continued ) Sample vocabulary (continued): DROP COLLECTION DROP TABLE DROP VIEW ALTER INSERT SELECT DELETE

7. 7 Introduction to SQL ( continued ) American National Standards Institute (ANSI) prescribes a standard SQL Several SQL dialects exist Oracle, MySQL, Access etc

8. 8 Data Manipulation Commands * Ignore Insert command for now *

9. 9 Sample Table: PART PART NUMBER PART DESC ON HANDCLASSWAREHOUSEPRICE AX12Iron104HW323.95 AZ52Dartboard20SG212.95 BA74Basketball40SG129.95 BH22Cornpopper95HW324.95 BT04GasGrill11AP2149.99 BZ66Washwer52AP3399.99 CA14Gridle78HW339.99 CB03Bike44SG1299.99 CX11Blender112HW322.95 CZ81Treadmill68SG2349.99

10. 10 Listing Table Rows SELECT Used to list contents of table Syntax SELECT Field1, Field 2,… FROM tablename WHERE Condition 1 AND/OR Condition 2 ORDER BY Field1, Field 2,…

11. 11 Listing Table Rows At a minimum, must specify what you want to select and where you want to select it from SELECT PART_NUMBER FROM PART

12. 12 Listing Table Rows, specifying a specific field name

13. 13 Listing All Table Rows Asterisk can be used as wildcard character to list all attributes SELECT * FROM PART

14. 14 Listing Table Rows with * to represent all field names

15. 15 Selecting Rows with Comparison Operators Select partial table contents by placing restrictions on rows to be included in output Add conditional restrictions to the SELECT statement, using WHERE clause SELECT * FROM PART WHERE ON_HAND > 30

16. 16 Listing Table Rows with * to represent all field names

17. 17 Comparison Operators

18. 18 Selecting Rows with Comparison Operators SELECT * FROM PART WHERE PART_NUMBER = ‘AX12’ Note criteria is in Parenthesis – PART_NUMBER is a character field

19. 19 Sorting Output Data is displayed in the order which it was added to the tables initially To change the order the data is displayed in, use the ORDER BY clause in the SELECT statement SELECT * FROM PART ORDER BY ON_HAND

20. 20 Sorting Output – Single Column SELECT * FROM PART ORDER BY ON_HAND

21. 21 Sorting Output – Multiple Columns SELECT * FROM PART ORDER BY PRICE, PART_NUMBER Note how boat name is sorted within owner num

22. 22 Sorting Output Data is displayed in the order which it was added to the tables initially To sort data in descending order, use the DESC keyword after each field specified in the ORDER BY clause that is to be displayed in descending order

23. 23 In Summary SELECT statement Used to list contents of table Syntax SELECT Field1, Field 2,… FROM tablename WHERE Condition 1 AND/OR Condition 2 ORDER BY Field1, Field 2,…

24. 24 Comparison Operators