The ROWID datatype in Oracle PL/SQL is used to store the address of a row in a database table. It is a unique identifier for each row that allows the database to quickly access the required data without performing a full table scan.
A ROWID is a binary string that represents the physical address of a row in the database file. It consists of the block number, row number within the block, and datafile number. This information makes it possible to quickly retrieve the required data using an indexed access to the data.
ROWID can be used in a SELECT statement to retrieve the row address of a particular row in a table. For example, the following statement returns the ROWID of the rows in the “employees” table:
SELECT ROWID, first_name, last_name FROM employees;
In PL/SQL, ROWID can be used in an UPDATE statement to update specific rows in a table based on their ROWID. This can be useful when you want to update specific rows in a large table that do not have a unique identifier. For example, the following statement updates the salary of an employee based on their ROWID:
UPDATE employees SET salary = salary + 1000 WHERE ROWID = 'AAAX3KAAEAAAAABAAB';
It is important to note that ROWID can change when a row is updated, so it should not be used as a permanent identifier for a row in a table. Instead, it is recommended to use a primary key or other unique identifier to identify a row in a table.
In conclusion, the ROWID datatype in Oracle PL/SQL provides a quick and efficient way to access specific rows in a database table. It should be used with caution as its value can change, and it is recommended to use a primary key or other unique identifier to identify a row in a table.