DB2 compatibility: the DB2 fetch-first-clause is supported.

h2/src/main/org/h2/command/Parser.java

@@ -1354,33 +1354,34 @@ public class Parser {
             command.setOrder(orderList);
             currentSelect = oldSelect;
         }
-        int test;
-//        if (database.getMode().supportOffsetFetch) {
-//            if (readIf("OFFSET")) {
-//                Select temp = currentSelect;
-//                // make sure aggregate functions will not work here
-//                currentSelect = null;
-//                command.setOffset(readExpression().optimize(session));
-//                if (!readIf("ROW")) {
-//                    read("ROWS");
-//                }
-//                currentSelect = temp;
-//            }
-//            if (readIf("FETCH")) {
-//                Select temp = currentSelect;
-//                // make sure aggregate functions will not work here
-//                currentSelect = null;
-//                if (readIf("FIRST")) {
-//                    Expression limit = readExpression().optimize(session);
-//                    command.setLimit(limit);
-//                    if (!readIf("ROW")) {
-//                        read("ROWS");
-//                    }
-//                    readIf("ONLY");
-//                }
-//                currentSelect = temp;
-//            }
-//        }
+        if (database.getMode().supportOffsetFetch) {
+            // make sure aggregate functions will not work here
+            Select temp = currentSelect;
+            currentSelect = null;
+            
+            // http://sqlpro.developpez.com/SQL2008/
+            if (readIf("OFFSET")) {
+                command.setOffset(readExpression().optimize(session));
+                if (!readIf("ROW")) {
+                    read("ROWS");
+                }
+            }
+            if (readIf("FETCH")) {
+                read("FIRST");
+                if (readIf("ROW")) {
+                    command.setLimit(ValueExpression.get(ValueInt.get(1)));
+                } else {
+                    Expression limit = readExpression().optimize(session);
+                    command.setLimit(limit);
+                    if (!readIf("ROW")) {
+                        read("ROWS");
+                    }
+                }
+                read("ONLY");
+            }
+            
+            currentSelect = temp;
+        }
         if (readIf("LIMIT")) {
             Select temp = currentSelect;
             // make sure aggregate functions will not work here

h2/src/main/org/h2/engine/Mode.java

@@ -132,6 +132,7 @@ public class Mode {
         add(mode);
 
         mode = new Mode("DB2");
+        mode.supportOffsetFetch = true;
         add(mode);
 
     }

h2/src/test/org/h2/test/testSimple.in.txt

+SET MODE DB2;
+SELECT * FROM SYSTEM_RANGE(1, 100) OFFSET 99 ROWS;
+> 100;
+SELECT * FROM SYSTEM_RANGE(1, 100) OFFSET 50 ROWS FETCH FIRST 1 ROW ONLY;
+> 51;
+SELECT * FROM SYSTEM_RANGE(1, 100) FETCH FIRST 1 ROWS ONLY;
+> 1;
+SELECT * FROM SYSTEM_RANGE(1, 100) FETCH FIRST ROW ONLY;
+> 1;
+SET MODE REGULAR;
+
 CREATE TABLE Address (id NUMBER NOT NULL, city VARCHAR2(255), PRIMARY KEY (id));
 CREATE TABLE Person (id NUMBER NOT NULL, name VARCHAR2(255), ADDRESS_ID NUMBER, PRIMARY KEY (id));
 INSERT INTO PERSON (id, name) values (1, 'Frank');