From e5bbfbe4bf079488d78726af75962f2d7fa22e56 Mon Sep 17 00:00:00 2001
From: Lukas Eder <lukas.eder@gmail.com>
Date: Sun, 5 Aug 2012 23:23:49 +0200
Subject: [PATCH] [#1665] Add support for the empty GROUP BY () clause

---
 .../jooq/test/_/testcases/GroupByTests.java    |  3 +--
 .../java/org/jooq/impl/AbstractSubSelect.java  | 18 +++++++++++++++++-
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/jOOQ-test/src/org/jooq/test/_/testcases/GroupByTests.java b/jOOQ-test/src/org/jooq/test/_/testcases/GroupByTests.java
index 330d3c1ce4..54b97e302b 100644
--- a/jOOQ-test/src/org/jooq/test/_/testcases/GroupByTests.java
+++ b/jOOQ-test/src/org/jooq/test/_/testcases/GroupByTests.java
@@ -47,7 +47,6 @@ import static org.jooq.impl.Factory.groupingId;
 import static org.jooq.impl.Factory.groupingSets;
 import static org.jooq.impl.Factory.one;
 import static org.jooq.impl.Factory.rollup;
-import static org.jooq.impl.Factory.trueCondition;
 
 import java.util.Arrays;
 
@@ -101,7 +100,7 @@ extends BaseTest<A, AP, B, S, B2S, BS, L, X, DATE, BOOL, D, T, U, I, IPK, T658,
         assertEquals(1, (int) create().selectOne()
                                       .from(TBook())
                                       .groupBy()
-                                      .having(trueCondition())
+                                      .having("1 = 1")
                                       .fetchOne(0, Integer.class));
 
         // Test a simple group by query
diff --git a/jOOQ/src/main/java/org/jooq/impl/AbstractSubSelect.java b/jOOQ/src/main/java/org/jooq/impl/AbstractSubSelect.java
index 37f78c28ba..3f0550360f 100644
--- a/jOOQ/src/main/java/org/jooq/impl/AbstractSubSelect.java
+++ b/jOOQ/src/main/java/org/jooq/impl/AbstractSubSelect.java
@@ -37,6 +37,11 @@ package org.jooq.impl;
 
 import static java.util.Arrays.asList;
 import static org.jooq.SQLDialect.CUBRID;
+import static org.jooq.SQLDialect.DERBY;
+import static org.jooq.SQLDialect.HSQLDB;
+import static org.jooq.SQLDialect.MYSQL;
+import static org.jooq.SQLDialect.POSTGRES;
+import static org.jooq.SQLDialect.SQLITE;
 import static org.jooq.SQLDialect.SQLSERVER;
 import static org.jooq.impl.Factory.inline;
 import static org.jooq.impl.Factory.one;
@@ -511,7 +516,18 @@ implements
 
             // [#1665] Empty GROUP BY () clauses need parentheses
             if (getGroupBy().isEmpty()) {
-                context.sql("()");
+
+                // [#1681] TODO: Simulate this for Sybase ASE, Ingres
+
+                // Some dialects don't support empty GROUP BY () clauses
+                if (asList(CUBRID, DERBY, HSQLDB, MYSQL, POSTGRES, SQLITE).contains(context.getDialect())) {
+                    context.sql("1");
+                }
+
+                // Few dialects support the SQL standard empty grouping set
+                else {
+                    context.sql("()");
+                }
             }
             else {
                 context.sql(getGroupBy());