Implemented:

* Add missing file
* prepare for function/sequence aliases.

h2/src/main/org/h2/command/ddl/CreateSynonym.java

@@ -8,15 +8,11 @@ package org.h2.command.ddl;
 import org.h2.api.ErrorCode;
 import org.h2.command.CommandInterface;
 import org.h2.engine.Database;
-import org.h2.engine.DbObject;
 import org.h2.engine.Session;
 import org.h2.message.DbException;
 import org.h2.schema.Schema;
 import org.h2.table.TableSynonym;
 import org.h2.table.Table;
-import org.h2.util.New;
-
-import java.util.HashSet;
 
 /**
  * This class represents the statement
@@ -61,6 +57,21 @@ public class CreateSynonym extends SchemaCommand {
         // TODO: Check when/if meta data is unlocked...
         db.lockMeta(session);
 
+        // This call throws an exception if the table does not exist.
+        if (data.synonymForSchema.findTableOrView(session, data.synonymFor) != null) {
+            return createTableSynonym(db);
+        } else if (data.synonymForSchema.findFunction(data.synonymFor) != null) {
+            // TODO Implement function synonym
+        } else if (data.synonymForSchema.findSequence(data.synonymFor) != null) {
+            // TODO Implement sequence synonym
+        }
+
+        throw DbException.get(ErrorCode.TABLE_OR_VIEW_NOT_FOUND_1,
+                data.synonymForSchema.getName() + "." + data.synonymFor);
+
+    }
+
+    private int createTableSynonym(Database db) {
         Table old = getSchema().findTableOrView(session, data.synonymName);
         if (old != null) {
             if (orReplace && old instanceof TableSynonym) {
@@ -72,8 +83,6 @@ public class CreateSynonym extends SchemaCommand {
             }
         }
 
-        validateBackingTableExists();
-
         TableSynonym table;
 
         if (old != null) {
@@ -88,15 +97,8 @@ public class CreateSynonym extends SchemaCommand {
 
             db.addSchemaObject(session, table);
         }
-        return 0;
-    }
 
-    private void validateBackingTableExists() {
-        // This call throws an exception if the table does not exist.
-        if (data.synonymForSchema.findTableOrView(session, data.synonymFor) == null) {
-            throw DbException.get(ErrorCode.TABLE_OR_VIEW_NOT_FOUND_1,
-                    data.synonymForSchema.getName() + "." + data.synonymFor);
-        }
+        return 0;
     }
 
     public void setComment(String comment) {

h2/src/main/org/h2/command/ddl/DropSynonym.java

+/*
+ * Copyright 2004-2014 H2 Group. Multiple-Licensed under the MPL 2.0,
+ * and the EPL 1.0 (http://h2database.com/html/license.html).
+ * Initial Developer: H2 Group
+ */
+package org.h2.command.ddl;
+
+import org.h2.api.ErrorCode;
+import org.h2.command.CommandInterface;
+import org.h2.constraint.ConstraintReferential;
+import org.h2.engine.Database;
+import org.h2.engine.DbObject;
+import org.h2.engine.Right;
+import org.h2.engine.Session;
+import org.h2.message.DbException;
+import org.h2.schema.Schema;
+import org.h2.table.Table;
+import org.h2.table.TableView;
+
+/**
+ * This class represents the statement
+ * DROP SYNONYM
+ */
+public class DropSynonym extends SchemaCommand {
+
+    private String synonymName;
+    private boolean ifExists;
+
+    public DropSynonym(Session session, Schema schema) {
+        super(session, schema);
+    }
+
+    public void setSynonymName(String name) {
+        this.synonymName = name;
+    }
+
+    @Override
+    public int update() {
+        session.commit(true);
+        Table synonym = getSchema().findTableOrView(session, synonymName);
+        if (synonym == null) {
+            if (!ifExists) {
+                throw DbException.get(ErrorCode.TABLE_OR_VIEW_NOT_FOUND_1, synonymName);
+            }
+        } else {
+            if (!Table.SYNONYM.equals(synonym.getTableType())) {
+                throw DbException.get(ErrorCode.TABLE_OR_VIEW_NOT_FOUND_1, synonymName);
+            }
+            session.getUser().checkRight(synonym, Right.ALL);
+            synonym.lock(session, true, true);
+            session.getDatabase().removeSchemaObject(session, synonym);
+        }
+        return 0;
+    }
+
+    public void setIfExists(boolean ifExists) {
+        this.ifExists = ifExists;
+    }
+
+    @Override
+    public int getType() {
+        return CommandInterface.DROP_SYNONYM;
+    }
+
+}