How should the data type be correctly updated in an existing database table?

To correctly update the data type in an existing database table, the ALTER TABLE command is usually used. It is important to consider:

• Compatibility of old data with the new type.
• The possibility of temporarily creating a new column with the required type, transferring data, and deleting the old one.
• Creating a backup before making changes.

Example in SQL:

ALTER TABLE users ALTER COLUMN age TYPE BIGINT;

If changing the type may lead to data loss, it is better to create a new column, copy and convert the data, then rename the columns.