Facing 'error: null value in column "column_name" violates not-null constraint'. why?

This error indicates you're trying to insert a NULL value into a column that has a NOT NULL constraint.

Example:

ERROR:  null value in column "user_id" violates not-null constraint

Solution:

1. Provide a non-null value for the column.
2. If needed, modify the table's schema to allow NULLs (not recommended without a specific reason).
3. Adjust your insert or update query accordingly.