hsyuan commented on a change in pull request #1606: [CALCITE-3466] Do not drop
the "group by" clause of subquery in a select statement with "group by" clause
in JDBC adapter.
URL: https://github.com/apache/calcite/pull/1606#discussion_r350955938
##########
File path:
core/src/test/java/org/apache/calcite/rel/rel2sql/RelToSqlConverterTest.java
##########
@@ -321,6 +321,20 @@ private static String toSql(RelNode root, SqlDialect
dialect) {
.ok(expectedMySql);
}
+ @Test public void testSelectQueryWithGroupBySubQuery() {
+ String query = "select \"product_class_id\", count(\"product_id\")\n"
+ + "from (select \"product_class_id\", \"product_id\"\n"
+ + "from \"product\"\n"
+ + "group by \"product_class_id\", \"product_id\") as t\n"
+ + "group by \"product_class_id\"";
+ final String expected = "SELECT \"product_class_id\", COUNT(*)\n"
Review comment:
This is incorrect. `COUNT(*)` doesn't equal with `count("product_id")`, if
product_id is nullable.
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