Oracle / PLSQL: ORA-01440 Error Message

Learn the cause and how to resolve the ORA-01440 error message in Oracle.

Description

When you encounter an ORA-01440 error, the following error message will appear:

• ORA-01440: column to be modified must be empty to decrease precision or scale

Cause

You tried to execute a ALTER TABLE MODIFY statement on a numeric column to decrease precision or scale, but the column contained data. You can only modify the numeric column whose values are all NULL.

Resolution

The option(s) to resolve this Oracle error are:

Option #1

Execute an UPDATE statement to change all values in that column to NULL.

Option #2

Execute a DELETE statement to remove all rows from the table.

For example, if you had a table called suppliers defined as follows:

CREATE TABLE suppliers
( supplier_id number(5),
  discount number(5,2)
);

Then executed an INSERT statement as follows:

INSERT into suppliers
(supplier_id, discount)
VALUES (12345, 30.25);

And you tried to execute the following ALTER TABLE statement:

ALTER TABLE suppliers
 MODIFY discount number(4,2);

You would receive the following error message:

You could correct the error with either of the following solutions:

Solution #1

You can update the discount column to all NULLs. This only works if the discount field will accept NULL values.

UPDATE suppliers
SET discount = NULL;

Solution #2

You can remove all entries from the suppliers table.

DELETE FROM suppliers;

If you do decide to delete all entries from your suppliers table, you might want to make sure that you have a backup of the data.