Error 1056 is thrown when a nonaggregated column in the SELECT list is neither grouped nor wrapped in an aggregate function in a GROUP BY query.
MySQL Error 1056: ER_WRONG_GROUP_FIELD appears when a SELECT statement with GROUP BY includes a column that is not in the GROUP BY list or an aggregate. Add the column to GROUP BY or wrap it in an aggregate function to resolve the error.
Can't group on '%s'
Error 1056 fires when MySQL encounters a column in the SELECT clause that is not part of the GROUP BY list and is not wrapped by an aggregate such as COUNT(), SUM(), or MAX().
The optimizer cannot determine which row value to return for that column, so it halts execution and shows “Can't group on '%s'.”
The error occurs in MySQL 5.x and 8.x when ONLY_FULL_GROUP_BY SQL mode is enabled, which is the default in modern versions. Disabling the mode removes the error but risks nondeterministic results, so fixing the query is preferred.
When ONLY_FULL_GROUP_BY is active, MySQL follows the SQL standard strictly.
Every selected column must be functionally dependent on the GROUP BY keys or be aggregated. If the rule is violated, MySQL returns Error 1056.
Leaving the query unfixed may push developers to disable ONLY_FULL_GROUP_BY, leading to silent data inconsistencies. Correcting the query ensures deterministic, portable SQL and prevents logic bugs in reports, dashboards, and production code.
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Selecting a plain column that is omitted from the GROUP BY list triggers the error because MySQL cannot pick a single value per group.
Using a raw column instead of an aggregate function such as MAX(order_date) or SUM(amount) causes Error 1056 when grouping.
Upgrading to MySQL 5.7+ enables ONLY_FULL_GROUP_BY automatically, exposing legacy queries that previously executed without complaint.
Subqueries, views, or derived tables that hide GROUP BY logic can still surface the error when the outer query violates grouping rules.
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Disabling removes the error but can return random values from each group. Prefer fixing the query for correctness.
MySQL 5.7 enables ONLY_FULL_GROUP_BY by default. Legacy queries that relied on the older relaxed behavior now raise Error 1056.
ANY_VALUE() tells MySQL to pick an arbitrary value, silencing the error. Use it only when you are certain any row's value is acceptable.
Galaxy’s editor analyzes your query as you type, highlights nonaggregated columns, and provides one-click fixes to wrap them in aggregates or add them to GROUP BY.
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