[jOOQ/jOOQ#11009] Add support for the MySQL FIELD() function

jOOQ/src/main/java/org/jooq/impl/FieldFunction.java

@@ -0,0 +1,118 @@
+/*
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * Other licenses:
+ * -----------------------------------------------------------------------------
+ * Commercial licenses for this work are available. These replace the above
+ * ASL 2.0 and offer limited warranties, support, maintenance, and commercial
+ * database integrations.
+ *
+ * For more information, please visit: http://www.jooq.org/licenses
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ *
+ */
+package org.jooq.impl;
+
+import static org.jooq.impl.DSL.inline;
+import static org.jooq.impl.DSL.zero;
+import static org.jooq.impl.Names.N_FIELD;
+import static org.jooq.impl.QueryPartListView.wrap;
+import static org.jooq.impl.SQLDataType.INTEGER;
+import static org.jooq.impl.Tools.EMPTY_FIELD;
+import static org.jooq.impl.Tools.combine;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.jooq.Context;
+import org.jooq.Field;
+
+/**
+ * @author Lukas Eder
+ */
+final class FieldFunction<T> extends AbstractField<Integer> {
+
+    /**
+     * Generated UID
+     */
+    private static final long                 serialVersionUID = 2328293840567996891L;
+    private final QueryPartListView<Field<?>> arguments;
+
+    FieldFunction(Field<T> field, Field<T>[] arguments) {
+        super(N_FIELD, INTEGER);
+
+        this.arguments = wrap(combine(field, arguments));
+    }
+
+    @Override
+    public final void accept(Context<?> ctx) {
+        switch (ctx.family()) {
+
+
+
+
+            case MARIADB:
+            case MYSQL:
+                if (arguments.size() > 1)
+                    ctx.visit(N_FIELD).sql('(').visit(arguments).sql(')');
+                else
+                    acceptDefault(ctx);
+
+                break;
+
+            default:
+                acceptDefault(ctx);
+                break;
+        }
+    }
+
+    private final void acceptDefault(Context<?> ctx) {
+        int size = arguments.size();
+
+        if (size == 1) {
+            ctx.visit(zero());
+        }
+        else {
+            List<Field<?>> args = new ArrayList<>();
+            args.add(arguments.get(0));
+
+            for (int i = 1; i < size; i++) {
+                args.add(arguments.get(i));
+                args.add(inline(i));
+            }
+
+            args.add(inline(0));
+
+            ctx.visit(DSL.decode(
+                args.get(0),
+                args.get(1),
+                args.get(2),
+                (Object[]) args.subList(3, args.size()).toArray(EMPTY_FIELD)
+            ));
+        }
+    }
+}

jOOQ/src/main/java/org/jooq/impl/RowIsNull.java

@@ -127,8 +127,15 @@ final class RowIsNull extends AbstractCondition {
         if (row != null && EMULATE_NULL_ROW.contains(ctx.dialect()))
             ctx.visit(condition(row.fields()));
         else if (select != null && EMULATE_NULL_QUERY.contains(ctx.dialect())) {
-            Table<?> t = new AliasedSelect<>(select).as("t");
-            ctx.visit(inline(1).eq(selectCount().from(t).where(condition(t.fields()))));
+
+            // [#11011] Avoid the RVE IS NULL emulation for queries of degree 1
+            if (select.getSelect().size() == 1) {
+                acceptStandard(ctx);
+            }
+            else {
+                Table<?> t = new AliasedSelect<>(select).as("t");
+                ctx.visit(inline(1).eq(selectCount().from(t).where(condition(t.fields()))));
+            }
         }
         else
             acceptStandard(ctx);