Diagnosing and Fixing the ORA-00960 Error in Oracle

If you are encountering the ORA-00960 error in Oracle, it means that you are trying to add a column to a table that already contains data, but the column has not been defined with a default value. This can be a frustrating issue, but with the right diagnosis and fix, you can overcome it.

Diagnosing the ORA-00960 Error

When you encounter the ORA-00960 error, Oracle will provide you with a message that looks something like this:

ORA-00960: ambiguous column naming in SELECT list

This error message indicates that there is a problem with the column naming in your SQL statement. It could be caused by using a column name that exists in multiple tables in the query without specifying which table the column belongs to.

To diagnose the error, carefully review your SQL statement and check for any ambiguous column names. Make sure that each column is properly qualified with the table or alias it belongs to.

Fixing the ORA-00960 Error

There are a few different ways to fix the ORA-00960 error, depending on the specific situation. Here are some possible solutions:

1. Qualify the Column Names

If the error is caused by ambiguous column naming, you can fix it by qualifying the column names with the appropriate table or alias. For example:

SELECT employees.employee_id, departments.department_name FROM employees, departments WHERE employees.department_id = departments.department_id;

In this example, the column names are qualified with the table names (employees and departments) to avoid ambiguity.

2. Use Table Aliases

Another way to avoid ambiguous column naming is to use table aliases in your SQL statement. This can make the code more readable and help prevent naming conflicts. For example:

SELECT e.employee_id, d.department_name FROM employees e, departments d WHERE e.department_id = d.department_id;

In this example, the table aliases “e” and “d” are used to qualify the column names.

3. Check for Data Integrity

If you are trying to add a column to a table that already contains data, you may need to consider the data integrity implications of adding the column without a default value. Depending on your specific requirements, you may need to populate the new column with default values or update the existing data to comply with the new column requirements.

4. Review the Database Design

In some cases, the ORA-00960 error may be a symptom of a larger issue with the database design. Take the time to review the structure of your database and consider whether the addition of the new column aligns with the overall design and requirements of the system.


By carefully diagnosing the ORA-00960 error and applying the appropriate fix, you can overcome this issue and continue working with your Oracle database. Remember to review your SQL statements for ambiguous column naming, qualify column names with table names or aliases, and consider the data integrity and database design implications of adding a new column. With these steps, you can effectively address the ORA-00960 error and keep your Oracle database running smoothly.

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