In Oracle versions prior to 19c, if a table had only one partition, you could not drop that last partition directly.
The reason: Oracle treats the partitioned table and its partitions as tightly linked — if you dropped the last partition, you would basically delete the entire table, which is not allowed that way.

Before 19c, the workaround involved steps like:

Create a new non-partitioned table.

Copy data from the partitioned table into the new non-partitioned table (using INSERT INTO new_table SELECT * FROM partitioned_table).

Drop the old partitioned table.

Rename the new table to the original table name.

In Oracle 19c and above, Oracle introduced a simpler way:

ALTER TABLE with the MODIFY PARTITION clause using the **NONPARTITIONED ONLINE **keywords.

The syntax is:

ALTER TABLE table_name
MODIFY PARTITION partition_name
TO NONPARTITIONED ONLINE;

Meaning:

Oracle will convert the partitioned table into a normal non-partitioned table.

ONLINE ensures that the table is available during the operation (minimal downtime).

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Example:

Suppose your table is:

CREATE TABLE sales
(
id NUMBER,
sale_date DATE
)
PARTITION BY RANGE (sale_date)
(
PARTITION sales_q1 VALUES LESS THAN (TO_DATE('2025-04-01','YYYY-MM-DD'))
);

To remove partitioning now (after 19c), just run:

ALTER TABLE sales
MODIFY PARTITION sales_q1 TO NONPARTITIONED ONLINE;

After this, sales becomes a normal table without partitions.

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