![]() My proposal is to simply return the non-empty query and make the union a no-op set in this case. ORDER BY merely changes the sort order of the b-tree for. ![]() In the case of a distinct UNION the elimination of duplicate rows is done by accumulating the result set in a temporary b-tree where the entire result row is the key. MySQL seems to accept this query but it's most likely not the query the user expects the be executed. The reason is that the UNION ALL is implemented by adding the 'rows' from each of the subselects into a temporary table. umber" ORDER BY "queries_number"."id" DESC) ORDER BY (1) ASCĭjango.db.utils.DatabaseError: ORDER BY not allowed in subqueries of compound statements. 圎rror: multiple ORDER BY clauses not allowed Result in the following error on PostgresSQL: (SELECT "queries_number"."id", "queries_number"."num", "queries_number"."other_num", "queries_number"."another_num" FROM "queries_number" ORDER BY "queries_number"."id" ASC) ORDER BY (1) ASC Qs2 = ().union(qs1).order_by(‘pk’)Įxecuting qs2 result in the following query: If len(querysets) = 1 it will result in a pretty weird query throwing a database error when both querysets are ordered, another example recreating this in the test suite: ![]() The 'select-stmt' syntax diagram above attempts to show as much of the SELECT statement syntax as possible in a single diagram. ![]() A SELECT statement does not make any changes to the database. The result of a SELECT is zero or more rows of data where each row has a fixed number of columns. I noticed this error while implementing a dynamic union like this: The SELECT statement is used to query the database. ![]()
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