Introduction to Oracle ROWID Data Type

In Oracle database, the ROWID data type is a special data type used to identify a row in a table. Each ROWID value is unique and contains a file number, a data block number, and an offset of the row in the data block. By using ROWID, we can quickly locate a row of data in a table.

Syntax

The syntax for ROWID data type in Oracle is as follows:

ROWID

Use Cases

The ROWID data type can be used to quickly locate a row of data in a table in an Oracle database. ROWID is often used in DML operations such as UPDATE or DELETE statements to quickly locate the row to be updated or deleted. ROWID can also be used for table joins or data extraction operations in data warehousing or other large databases.

Examples

Here are two examples of using ROWID:

Example 1: Using ROWID to Locate a Row of Data in a Table

Create a table

CREATE TABLE employees (
  id NUMBER,
  name VARCHAR2(50),
  salary NUMBER
);

Insert data

INSERT INTO employees VALUES (1, 'Alice', 5000);
INSERT INTO employees VALUES (2, 'Bob', 6000);
INSERT INTO employees VALUES (3, 'Charlie', 7000);

Query the ROWID value of a row of data

SELECT ROWID FROM employees WHERE id = 2;

Update a row of data in the table using ROWID

UPDATE employees SET salary = 6500 WHERE ROWID = 'AAAR1gAAEAAAAFzAAA';

Delete a row of data in the table using ROWID

DELETE FROM employees WHERE ROWID = 'AAAR1gAAEAAAAFzAAA';

Example 2: Using ROWID for Table Joins

Create Table 1

CREATE TABLE orders (
  order_id NUMBER,
  customer_id NUMBER,
  amount NUMBER
);

Insert data

INSERT INTO orders VALUES (1, 101, 1000);
INSERT INTO orders VALUES (2, 102, 2000);
INSERT INTO orders VALUES (3, 103, 3000);

Create Table 2

CREATE TABLE customers (
  id NUMBER,
  name VARCHAR2(50),
  address VARCHAR2(50)
);

Insert data

INSERT INTO customers VALUES (101, 'Alice', '123 Main St');
INSERT INTO customers VALUES (102, 'Bob', '456 Elm St');
INSERT INTO customers VALUES (103, 'Charlie', '789 Oak St');

Use ROWID for table joins

SELECT o.order_id, o.amount, c.name
FROM orders o, customers c
WHERE o.customer_id = c.id
AND o.rowid = 'AAADWMAAEAAAAA6AAA';

Conclusion

In Oracle database, ROWID is a very useful data type that can be used to quickly locate a row of data in a table. ROWID can be used for DML operations such as UPDATE or DELETE statements, as well as for table joins or data extraction operations. However, in some cases, the ROWID value may change, for example, during table partitioning or rebuilding operations, so caution should be exercised when using ROWID.