JPA Criteria Builder的求和列顺序

Question

I have the following SQL query.

select colA, sum(colB) as colB from tableA group by colA order by colB desc;

I have used jpa criteria builder to build the query dynamically.

List<String> selectCols = new ArrayList<>();
selectCols.add("colA");
List<String> sumColumns = new ArrayList<>();
sumColumns.add("colB");
List<String> groupByColumns = new ArrayList<>();
groupByColumns.add("colA");
List<String> orderingColumns = new ArrayList<>();
orderingColumns.add("colB");

CriteriaBuilder builder = entityManager.getCriteriaBuilder();
CriteriaQuery<Tuple> cQuery = builder.createQuery(Tuple.class);
Root<T> root = cQuery.from(getDomainClass());

List<Selection<?>> selections = new ArrayList<>();
for (String column : selectCols) {
    selections.add(root.get(column).alias(column));
}

if (sumColumns != null) {
    for (String sumColumn : sumColumns) {
        selections.add(builder.sum(root.get(sumColumn)).alias(sumColumn));
    }
}

cQuery.multiselect(selections);

List<Expression<?>> groupByExpressions = new LinkedList<>();

for (String column : groupByColumns) {
    groupByExpressions.add(root.get(column));
}

cQuery.groupBy(groupByExpressions);

List<Order> orders = new ArrayList<>();

for (String orderCol : orderingColumns) {

    orders.add(builder.desc(root.get(orderCol)));

}

cQuery.orderBy(orders);

entityManager.createQuery(cQuery).getResultList();

I debugged and checked the exact sql statement that is getting executed.

select colA as col_1_0, sum(colB) as col_2_0 from tableA group by colA order by colB desc;

The resultant sql statement that is getting executed doesn't have the alias for colB as colB. I am using MySql. Surprisingly, this statement gets executed and I get proper results when sql mode is set to NO_ENGINE_SUBSTITUTION. But when the sql mode is ONLY_FULL_GROUP_BY, the database throws an error saying

Expression #1 of ORDER BY clause is not in GROUP BY clause and contains nonaggregated column 'colB' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by

I understand that in this mode, sql validates the query and my query fails. How do I create an alias with jpa criteria builder so that the actual statement getting executed contains a proper alias for the sum column?

Note: I use spring-data-jpa and this is a custom implementation of repository. I can manually write the query using @Query annotation but the nature of the queries are dynamic on group by, order by, where clauses and the select columns. Hence the need for a dynamic criteria builder implementation.

Answer 1

Try sorting over the aggregate. In my experience, column aliases usually can't be referenced in the query itself.

orders.add(builder.desc(builder.sum(sumColumn)));

Answer 2

i think so you have bug in orderingColumns , you schould add colA instead colB

or instead

for (String orderCol : orderingColumns) {
    orders.add(builder.desc(root.get(orderCol)));
}

you can use

orders.add(builder.desc(root.get("colA")));