SQL Error [937] [42000]: ORA-00937: not a single-group group function code example

Example: not a single-group group function

ORA-00937: not a single-group group function
Cause: A SELECT list cannot include both a group function, such as AVG, COUNT, MAX, MIN, SUM, STDDEV, or VARIANCE, and an individual column expression, unless the individual column expression is included in a GROUP BY clause.