Creating a Table (Transactions)

The Transactions table contains a row for each transaction involving a patron and a book (for example, someone checking a book out or returning a book). It includes two foreign key columns. You will use the Create Table dialog box to create the table declaratively; the table that you create will be essentially the same as if you had entered the following statement using the SQL Worksheet:

CREATE TABLE Transactions (
   transaction_id NUMBER PRIMARY KEY,
   patron_id CONSTRAINT for_key_patron_id
      REFERENCES patrons(patron_id),
   book_id CONSTRAINT for_key_book_id
      REFERENCES books(book_id),
   transaction_date DATE,
   transaction_type NUMBER);

To create the Transactions table, if you are not already connected, connect to the database as the user for the schema you are using for this tutorial. Right-click the Tables node in the schema hierarchy on the left side, select Create Table, and enter the following information. (If a tab or field is not mentioned, do not enter anything for it.)

Schema: Specify your current schema as the schema in which to create the table.

Name: Transactions

Create the table columns using the following information. After creating each column except the last one (transaction_type), click Add Column to add the next column. (If you accidentally click OK instead of Add Column, right-click the TRANSACTIONS table in the Connections navigator display, select Edit, and continue to add columns.)

Column Name	Type	Size	Other Information and Notes
transaction_id	NUMBER		Primary Key. (Unique transaction ID number, with values to be created using a trigger and sequence that will be created automatically)
patron_id	NUMBER		(Foreign key; must match a patron_id value in the Patrons table)
book_id	VARCHAR2	20	(Foreign key; must match a book_id value in the Books table)
transaction_date	DATE		(Date and time of the transaction)
transaction_type	NUMBER		(Numeric code indicating the type of transaction, such as 1 for checking out a book)

After you have entered the last column (transaction_type), check Show Advanced Options (next to Schema). This displays additional tabs for more table options. For this table, you will use the Primary Key and Foreign Keys tabs.

Primary Key tab

Because you have already specified the column for the primary key, you will use this tab only to specify that the primary key column values are to be populated automatically. This convenient approach uses a trigger and a sequence (both created automatically by SQL Developer), and ensures that each transaction ID value is unique.

Populate Primary Key Column: TRANSACTION_ID

From: (Accept the defaults.)

Trigger Name: (Either accept the default or enter a name for the before-insert trigger that will be created automatically.)

Foreign Keys tab

1. Click Add to create the first of the two foreign keys for the Transactions table.

Name: for_key_patron_id

Referenced Schema: Name of the schema containing the table with the primary key or unique constraint to which this foreign key refers. Use the schema you have been using for this tutorial.

Referenced Table: PATRONS

Referenced Constraint: Name (generated by Oracle) of the primary key constraint for the Patrons table. (Might be a name with a format like PATRONS_PK.) Be sure that the Referenced Column on PATRONS displayed value is PATRON_ID after you select the Referenced Constraint.

Associations: Local Column: PATRON_ID

Associations: Referenced Column on PATRONS: PATRON_ID

2. Click Add to create the second of the two foreign keys for the Transactions table.

Name: for_key_book_id

Referenced Schema: Name of the schema containing the table with the primary key or unique constraint to which this foreign key refers. Use the schema you have been using for this tutorial.

Referenced Table: BOOKS

Referenced Constraint: Name (generated by Oracle) of the primary key constraint for the Books table. (Might be a name with a format like BOOKS_PK.) Be sure that the Referenced Column on BOOKS displayed value is BOOK_ID after you select the Referenced Constraint.

Associations: Local Column: BOOK_ID

Associations: Referenced Column on BOOKS: BOOK_ID

3. Click OK to finish creating the table.

You have finished creating all the tables. To create a sequence for use in generating unique primary key values for the Patrons table, go to Creating a Sequence.