IBM DB2 and Apache Derby compatibility: support the pseudo-table SYSIBM.SYSDUMMY1.

h2/src/docsrc/html/changelog.html

@@ -18,7 +18,8 @@ Change Log
 <h1>Change Log</h1>
 
 <h2>Next Version (unreleased)</h2>
-<ul><li>ROWNUM() did not work in combination with IN(..). The following query did not work as expected:
+<ul><li>IBM DB2 and Apache Derby compatibility: support the pseudo-table SYSIBM.SYSDUMMY1.
+</li><li>ROWNUM() did not work in combination with IN(..). The following query did not work as expected:
     select * from (select rownum r from test) where r in (1, 2).
 </li><li>H2 Console autocomplete: the autocomplete feature didn't support quoted names.
 </li><li>It is now longer allowed to create an index on a CLOB or BLOB column

h2/src/docsrc/html/features.html

@@ -1016,6 +1016,7 @@ or the SQL statement <code>SET MODE DB2</code>.
     as an alternative for <code>LIMIT .. OFFSET</code>.
 </li><li>Concatenating <code>NULL</code> with another value
     results in the other value.
+</li><li>Support the pseudo-table SYSIBM.SYSDUMMY1.
 </li></ul>
 
 <h3>Derby Compatibility Mode</h3>
@@ -1030,6 +1031,7 @@ or the SQL statement <code>SET MODE Derby</code>.
     That means only one row with <code>NULL</code> in one of the columns is allowed.
 </li><li>Concatenating <code>NULL</code> with another value
     results in the other value.
+</li><li>Support the pseudo-table SYSIBM.SYSDUMMY1.    
 </li></ul>
 
 <h3>HSQLDB Compatibility Mode</h3>

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

@@ -607,6 +607,8 @@ public class Parser {
             if (equalsToken("SESSION", schemaName)) {
                 // for local temporary tables
                 schema = database.getSchema(session.getCurrentSchemaName());
+            } else if (database.getMode().sysDummy1 && "SYSIBM".equals(schemaName)) {
+                // IBM DB2 and Apache Derby compatibility: SYSIBM.SYSDUMMY1
             } else {
                 throw DbException.get(ErrorCode.SCHEMA_NOT_FOUND_1, schemaName);
             }
@@ -1067,6 +1069,8 @@ public class Parser {
                 }
             } else if (equalsToken("DUAL", tableName)) {
                 table = getDualTable(false);
+            } else if (database.getMode().sysDummy1 && equalsToken("SYSDUMMY1", tableName)) {
+                table = getDualTable(false);
             } else {
                 table = readTableOrView(tableName);
             }

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

@@ -104,6 +104,11 @@ public class Mode {
      */
     public boolean uniqueIndexSingleNullExceptAllColumnsAreNull;
 
+    /**
+     * Support the pseudo-table SYSIBM.SYSDUMMY1.
+     */
+    public boolean sysDummy1;
+
     /**
      * Text can be concatenated using '+'.
      */
@@ -119,11 +124,13 @@ public class Mode {
         mode = new Mode("DB2");
         mode.aliasColumnName = true;
         mode.supportOffsetFetch = true;
+        mode.sysDummy1 = true;
         add(mode);
 
         mode = new Mode("Derby");
         mode.aliasColumnName = true;
         mode.uniqueIndexSingleNull = true;
+        mode.sysDummy1 = true;
         add(mode);
 
         mode = new Mode("HSQLDB");

h2/src/test/org/h2/test/db/TestCompatibility.java

@@ -40,6 +40,8 @@ public class TestCompatibility extends TestBase {
         testUniqueIndexOracle();
         testHsqlDb();
         testMySQL();
+        testDB2();
+        testDerby();
         testPlusSignAsConcatOperator();
 
         conn.close();
@@ -224,4 +226,37 @@ public class TestCompatibility extends TestBase {
 
     }
 
+    private void testDB2() throws SQLException {
+        conn = getConnection("compatibility;MODE=DB2");
+        ResultSet res = conn.createStatement().executeQuery("SELECT 1 FROM sysibm.sysdummy1");
+        res.next();
+        assertEquals("1", res.getString(1));
+        conn.close();
+        conn = getConnection("compatibility;MODE=MySQL");
+        try {
+            conn.createStatement().executeQuery("SELECT 1 FROM sysibm.sysdummy1");
+            fail();
+        } catch (SQLException e) {
+            // can't lookup sysibm.sysdummy1 on mode=MySQL etc.
+        }
+        conn.close();
+        conn = getConnection("compatibility");
+    }
+
+    private void testDerby() throws SQLException {
+        conn = getConnection("compatibility;MODE=Derby");
+        ResultSet res = conn.createStatement().executeQuery("SELECT 1 FROM sysibm.sysdummy1");
+        res.next();
+        assertEquals("1", res.getString(1));
+        conn.close();
+        conn = getConnection("compatibility;MODE=PostgreSQL");
+        try {
+            conn.createStatement().executeQuery("SELECT 1 FROM sysibm.sysdummy1");
+            fail();
+        } catch (SQLException e) {
+            // can't lookup sysibm.sysdummy1 on mode=MySQL etc.
+        }
+        conn.close();
+        conn = getConnection("compatibility");
+    }
 }