How to fix ERROR 1056: Can't group on column in MySQL

The most direct solution is to include every column in the GROUP BY that appears in the SELECT clause without an aggregate function.

Before (causes ERROR 1056):

SELECT name, address, MAX(age)
FROM users
GROUP BY name;

After (correct):

SELECT name, address, MAX(age)
FROM users
GROUP BY name, address;

This ensures MySQL knows exactly which value to return for each column in each group.

If you don't need all columns in the GROUP BY, wrap them in an aggregate function. Choose the appropriate function based on what value you want:

-- Get first address value
SELECT name, MIN(address), MAX(age)
FROM users
GROUP BY name;

-- Or use ANY_VALUE() when any value is acceptable
SELECT name, ANY_VALUE(address), MAX(age)
FROM users
GROUP BY name;

The ANY_VALUE() function explicitly tells MySQL to pick an arbitrary value, which is useful when you only care about the grouped column.

If a selected column is functionally dependent on a GROUP BY column (like when GROUP BY uses a primary key or unique NOT NULL column), MySQL will allow it without aggregation:

-- If user_id is a primary key, address is allowed without aggregation
SELECT user_id, address, MAX(age)
FROM users
GROUP BY user_id;

This works because each user_id uniquely identifies one row, so address has only one possible value per group. Check your schema to identify such columns.

For MySQL 8.0+, window functions provide an alternative to GROUP BY that doesn't require all columns to be aggregated:

-- Get each user with their age and max age in their group
SELECT
  name,
  address,
  age,
  MAX(age) OVER (PARTITION BY department) as max_dept_age
FROM users;

This approach avoids GROUP BY entirely while still performing grouped calculations.