1. Starting with Oracle SQL Plus

2. Today in the lab… Connect to SQL Plus – your schema. Set up two tables. Find the tables in the catalog. Insert four rows into the base table. Insert two rows into the detail table. Alter the structure of the detail table, to constrain its contents. If this doesn’t work, why? What can you do to make it work?

3. Find your feet… Oracle SQL Plus –Are you in the correct lab? –Introduce yourselves to Oracle Each person has an individual schema (R,W,U,D) In your INDIVIDUAL schema, use the Data Definition Language commands to create, populate, update and alter 2 joined tables.

4. Find the application Through the Start menu, find –Programs –Oracle client –Application Development –SQL Plus (icon opposite)

5. This is an example Don’t forget to get a username and password for your SCHEMA. The Host string defines the DATABASE. This one won’t work for you!

6. An example from Oracle 10g

7. About the interface… The interface is VERY basic. It is similar to a very old model of command line interface. Each line is transacted immediately. It takes a bit of getting used to! Using the examples on the following slides, create two tables.

8. Example

9. …About the interface To exit the application, type in EXIT To save your work: It is messy trying to save in this environment. The best thing to do is to open Notepad as well as SQL Plus and copy from one to the other. Note that the full path name needs to be entered, so keep path names SHORT!!.

10. SQL SQL or Standard Query Language is used widely to access databases. Implemented SQL (Oracle, MS SQL Server, Access) varies a little from the standard, but is reasonably standard It consists of a data definition language - DDL (Create, Alter, Drop) And a Data Manipulation Language - DML (Select, Union, Update, Delete, Insert Into, Select Into, Transform, Parameter)

11. The CREATE command Creates tables in your schema. The basic Create statement: CREATE TABLE table_name ( {column_name data_type} ) [] optional, {} one or more, lower case – user supplied names, upper case reserved words, [|] either or, () are part of the syntax. See www.ss64.com/orasyntax/datatypes.html for a comprehensive list and description of data types.www.ss64.com/orasyntax/datatypes.html

12. Adding constraints To make one the attributes a primary key, put a CONSTRAINT on the table, by adding: PRIMARY KEY (column_name).

13. Constraints Constraints can be imposed when the table is being created, in the create statement. Constraints can be on the column or the table. Column constraints can be listed after the column data type; e.g. NOT NULL, UNIQUE, PRIMARY KEY. –Note: Primary Key doesn’t need unique. Other constraints can be added after all columns have been declared, by ALTERing the table. These can include –primary keys, including compound primary keys, or –foreign keys.

14. Exercise Set up two tables. –Product with columns ProductCode 4 digits, ProductName 15 characters, ProductPrice Decimal – 4 digits with two after the decimal place. The product code is the primary key. –Supplier with columns SupplierId 4 digits, SName 15 characters. SupplierId is the primary key. Find the tables in the catalog. –To find tables in the catalog, you manipulate the SQLPlus buffer. –Select * from cat See end of previous example.

15. Data Manipulation Language Data Manipulation language (DML) allows you to manipulate the contents of the tables in you schema, rather than the definition. DML includes Insert Delete Update Select

16. Insert statement This adds data to the table. Either a full row can be added, or values can be put in individual columns. NOTE: If only some of the columns are given values, the remainder of the columns have an undefined status of NULL. If a column is constrained by the ‘NOT NULL’ constraint, every insert to the owning table must provide a value for that column, unless a DEFAULT value is provided for the table.

17. Example insert (full version)

18. Exercise Insert four rows into the supplier table, ensuring that the data types and constraints are respected. Insert two rows into the product table, as above. Check the contents of both tables by –Select * from tablename; –Note that the semicolon ends the statement.

19. Altering tables Alter is part of the data definition language. Alter allows a column to be added or dropped from the table. –ALTER TABLE customer ADD COLUMN server NUMBER(7) DEFAULT 1234567; Alter allows a constraint to be added or removed from a table. –ALTER TABLE customer ADD CONSTRAINT servedby FOREIGN KEY server REFERENCES staff(staffId);

20. Exercise Use the Alter command to: –Add a new column called ‘supplier’ of type 4 digits, to the product table, with a default value of 1234. –Add a constraint to the product table, making the new ‘supplier’ field a foreign key, referencing the SupplierId in the Supplier table.

21. Lessons? If this doesn’t work, why not? What can you do to make it work?

23. Manipulating the buffer To terminate an entry, use ; or, on a new line, use / Append text or a text adds text to the end of a line. Change /old/new or C /old/new changes old to new in a line. Change /text or C /text deletes text from a line. Clear buffer or cl buff deletes all lines. Del deletes a line Get file loads the contents of a fine named file into the buffer. Input or i add one or more lines Input text adds a line consisting of text. List or l lists all lines in buffer List n or l n or n lists one line and makes it the current line. List * or l * lists the current line List last or l last lists the last line List m n or l m n lists lines m through n Save file or sav file saves the contents of the buffer to a file named file.

24. To list columns select table_name, column_name from user_tab_columns; To describe a table: –Desc ;

25. Errors * ERROR at line 1: ORA-02291: integrity constraint (BUILDER.REL658) violated - parent key not found What does this mean?