Use this SQL query :delete from student_tab A where ROWID > ( select min(ROWID) from student_tab B where A.roll_number = B.roll_number);Note : Table Name = student_tab Key to table = roll_number
Yes ,, we can delete entries from a table based on the date column,,Only we have to mention the date format or other wise we'll have to make use of the sys date.
This value causes the optimizer to the cost-based approach for all SQL statements in the session regardless of the presence of statistics and to optimize with a goal of best throughput.
A Read-Only transaction ensures that the results of each query executed in the transaction are consistant with respect to the same point in time.
The combination of the steps the optimizer chooses to execute a statement is called an execution plan.
For long transactions that contain many SQL statements, intermediate markers or savepoints can be declared which can be used to divide a transaction into smaller parts. This allows the option of later rolling back all work performed from the current point in the transaction to a declared savepoint within the transaction.