detailed ppt on sql

1. SQL Server - Design and Implementation

7. Basic structure of an SQL query

8. Table Design Rows describe the Occurrence of an Entity Columns describe one characteristic of the entity Tables are the basic structure where data is stored in the database. Name Address Jane Doe 123 Main Street John Smith 456 Second Street Mary Poe 789 Third Ave

11. Default For example, if we create a table as below: CREATE TABLE Student (Student_ID integer Unique, Last_Name varchar (30), First_Name varchar (30), Score DEFAULT 80); and execute the following SQL statement, INSERT INTO Student (Student_ID, Last_Name, First_Name) values ('10','Johnson','Rick'); The table will look like the following: Even though we didn't specify a value for the "Score" column in the INSERT INTO statement, it does get assigned the default value of 80 since we had already set 80 as the default value for this column. Student_ID Last_Name First_Name Score 10 Johnson Rick 80

12. Unique For example, in the following CREATE TABLE statement, CREATE TABLE Customer (SID integer Unique, Last_Name varchar (30), First_Name varchar(30)); column "SID" has a unique constraint, and hence cannot include duplicate values. Such constraint does not hold for columns "Last_Name" and "First_Name". So, if the table already contains the following rows: Executing the following SQL statement, INSERT INTO Customer values ('3','Lee','Grace'); will result in an error because '3' already exists in the SID column, thus trying to insert another row with that value violates the UNIQUE constraint. SID Last_Name First_Name 1 Johnson Stella 2 James Gina 3 Aaron Ralph

14. Primary Key A primary key is used to uniquely identify each row in a table. A primary key can consist of one or more fields on a table. When multiple fields are used as a primary key, they are called a composite key. CREATE TABLE Customer (SID integer PRIMARY KEY, Last_Name varchar(30), First_Name varchar(30));

15. Foreign Key A foreign key is a field (or fields) that points to the primary key of another table. The purpose of the foreign key is, only values that are supposed to appear in the database are permitted. CREATE TABLE ORDERS (Order_ID integer primary key, Order_Date datetime, Customer_SID integer references CUSTOMER(SID), Amount double); In the above example, the Customer_SID column in the ORDERS table is a foreign key pointing to the SID column in the CUSTOMER table.

20. Using SQL SQL statements can be embedded into a program (cgi or perl script, Visual Basic, C#, MS Access) OR SQL statements can be entered directly at the command prompt of the SQL software being used (such as mySQL)

21. Using SQL To begin, you must first CREATE a database using the following SQL statement: CREATE DATABASE database_name Depending on the version of SQL being used the following statement is needed to begin using the database: USE database_name

24. Using SQL SELECT auth_name, auth_city FROM publishers If you only want to display the author’s name and city from the following table: auth_id auth_name auth_city auth_state 123456789 Jane Doe Dearborn MI 000000001 John Smith Taylor MI auth_name auth_city Jane Doe Dearborn John Smith Taylor

25. Using SQL DELETE from authors WHERE auth_name=‘John Smith’ To delete data from a table, use the DELETE statement: auth_id auth_name auth_city auth_state 123456789 Jane Doe Dearborn MI 000000001 John Smith Taylor MI

26. Using SQL UPDATE authors SET auth_name=‘hello’ To Update information in a database use the UPDATE keyword Hello Hello Sets all auth_name fields to hello auth_id auth_name auth_city auth_state 123456789 Jane Doe Dearborn MI 000000001 John Smith Taylor MI

27. Using SQL ALTER TABLE authors ADD birth_date datetime null To change a table in a database use ALTER TABLE. ADD adds a characteristic. ADD puts a new column in the table called birth_date Type Initializer auth_id auth_name auth_city auth_state 123456789 Jane Doe Dearborn MI 000000001 John Smith Taylor MI birth_date . .

28. Using SQL ALTER TABLE authors DROP birth_date To delete a column or row, use the keyword DROP DROP removed the birth_date characteristic from the table auth_id auth_name auth_city auth_state 123456789 Jane Doe Dearborn MI 000000001 John Smith Taylor MI auth_state . .

29. Using SQL DROP DATABASE authors The DROP statement is also used to delete an entire database. DROP removed the database and returned the memory to system auth_id auth_name auth_city auth_state 123456789 Jane Doe Dearborn MI 000000001 John Smith Taylor MI

30. Normalization The process of removing redundant data by creating relations between tables is known as Normalization. Normalization process uses formal methods to design the database in interrelated tables.

31. Design DB