Oracle / PLSQL: ORA-00979 Error Message

Learn the cause and how to resolve the ORA-00979 error message in Oracle.

Description

When you encounter an ORA-00979 error, the following error message will appear:

• ORA-00979: not a GROUP BY expression

Cause

You tried to execute a SELECT statement that included a GROUP BY function (ie: MIN Function, MAX Function, SUM Function, COUNT Function) and an expression in the SELECT list that was not in the GROUP BY clause.

Resolution

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

Option #1

Rewrite the SELECT statement so that the column or expression listed in the SELECT list is also found in the GROUP BY clause.

Option #2

Remove the GROUP BY function (ie: MIN Function, MAX Function, SUM Function, COUNT Function) from the SELECT statement.

Option #3

Remove the expression from the SELECT list that was not in the GROUP BY clause.

For example, if you had tried to execute the following SELECT statement:

SELECT department, company, MIN(salary) AS "Lowest salary"
FROM employees
GROUP BY department;

You would receive the following error message:

You could correct this by including company in the GROUP BY clause as follows:

SELECT department, company, MIN(salary) AS "Lowest salary"
FROM employees
GROUP BY department, company;