DROP VIEW now supports the CASCADE and RESTRICT clauses

CREATE VIEW now supports the OR REPLACE clause

h2/src/docsrc/help/help.csv

@@ -748,7 +748,7 @@ DROP USER TOM
 "
 
 "Commands (DDL)","DROP VIEW","
-DROP VIEW [ IF EXISTS ] viewName [RESTRICT | CASCADE ]
+DROP VIEW [ IF EXISTS ] viewName [ RESTRICT | CASCADE ]
 ","
 Drops a view, and all dependent views if the CASCADE clause is used.
 The command will fail if dependent views exist and the RESTRICT clause is used. This is the default.

h2/src/docsrc/html/changelog.html

@@ -35,6 +35,8 @@ Change Log
 </li><li>Version 1.2.137 could still not be converted to Java 1.4
     (because the Retrotranslator doesn't support BigDecimal.precision).
 </li><li>Cluster: non-admin users could not connect when one of the cluster node was stopped. Issue 206.
+</li><li>DROP VIEW now supports the CASCADE and RESTRICT clauses (patch from Kerry Sainsbury)
+</li><li>CREATE VIEW now supports the OR REPLACE clause (patch from Kerry Sainsbury)
 </li></ul>
 
 <h2>Version 1.2.137 (2010-06-06)</h2>
@@ -383,7 +385,7 @@ Change Log
     This could cause the server-less multi-connection mode to fail.
 </li><li>Result sets larger than 2 GB threw an exception "Negative seek offset". Fixed.
 </li><li>If the system property h2.check was set to false, an ArrayIndexOutOfBoundsException could occur.
-</li><li>Alter table is now supported even if a table has views defined.
+</li><li>Alter table is now supported even if a table has views defined. (Patch from Kerry Sainsbury).
 </li><li>Fulltext search: exceptions within the fulltext search package had the wrong SQL state.
 </li><li>The Lucene fulltext search ignored transaction rollback. Fixed using a trigger on rollback.
 </li><li>Trigger can now be called on rollback.

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

@@ -1154,6 +1154,10 @@ public class Parser {
             command.setViewName(viewName);
             ifExists = readIfExists(ifExists);
             command.setIfExists(ifExists);
+            Integer dropAction = parseCascadeOrRestrict();
+            if (dropAction != null) {
+                command.setDropAction(dropAction);
+            }
             return command;
         } else if (readIf("ROLE")) {
             boolean ifExists = readIfExists(false);
@@ -3533,9 +3537,15 @@ public class Parser {
     }
 
     private Prepared parseCreate() {
+        boolean orReplace = false;
+        if (readIf("OR")) {
+           read("REPLACE");
+           orReplace = true;
+        }
+
         boolean force = readIf("FORCE");
         if (readIf("VIEW")) {
-            return parseCreateView(force);
+            return parseCreateView(force, orReplace);
         } else if (readIf("ALIAS")) {
             return parseCreateFunctionAlias(force);
         } else if (readIf("SEQUENCE")) {
@@ -3951,7 +3961,7 @@ public class Parser {
         return query;
     }
 
-    private CreateView parseCreateView(boolean force) {
+    private CreateView parseCreateView(boolean force, boolean orReplace) {
         boolean ifNotExists = readIfNoExists();
         String viewName = readIdentifierWithSchema();
         CreateView command = new CreateView(session, getSchema());
@@ -3959,6 +3969,8 @@ public class Parser {
         command.setViewName(viewName);
         command.setIfNotExists(ifNotExists);
         command.setComment(readCommentIf());
+        command.setOrReplace(orReplace);
+        command.setForce(force);
         if (readIf("(")) {
             String[] cols = parseColumnList();
             command.setColumnNames(cols);
@@ -4613,11 +4625,11 @@ public class Parser {
     }
 
     private int parseAction() {
-        if (readIf("CASCADE")) {
-            return ConstraintReferential.CASCADE;
-        } else if (readIf("RESTRICT")) {
-            return ConstraintReferential.RESTRICT;
-        } else if (readIf("NO")) {
+        Integer result = parseCascadeOrRestrict();
+        if (result != null) {
+            return result;
+        }
+        if (readIf("NO")) {
             read("ACTION");
             return ConstraintReferential.RESTRICT;
         } else {
@@ -4630,6 +4642,16 @@ public class Parser {
         }
     }
 
+    private Integer parseCascadeOrRestrict() {
+        if (readIf("CASCADE")) {
+            return ConstraintReferential.CASCADE;
+        } else if (readIf("RESTRICT")) {
+            return ConstraintReferential.RESTRICT;
+        } else {
+            return null;
+        }
+    }
+
     private Prepared parseAlterTableAddConstraintIf(String tableName, Schema schema) {
         String constraintName = null, comment = null;
         boolean ifNotExists = false;

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

@@ -6,15 +6,21 @@
  */
 package org.h2.command.ddl;
 
+import org.h2.command.Prepared;
 import org.h2.command.dml.Query;
 import org.h2.constant.ErrorCode;
 import org.h2.engine.Constants;
 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.Table;
 import org.h2.table.TableView;
 
+import java.util.ArrayList;
+import java.util.List;
+
 /**
  * This class represents the statement
  * CREATE VIEW
@@ -28,6 +34,8 @@ public class CreateView extends SchemaCommand {
     private String[] columnNames;
     private String comment;
     private boolean recursive;
+    private boolean orReplace;
+    private boolean force;
 
     public CreateView(Session session, Schema schema) {
         super(session, schema);
@@ -45,14 +53,49 @@ public class CreateView extends SchemaCommand {
         this.select = select;
     }
 
+    public void setIfNotExists(boolean ifNotExists) {
+        this.ifNotExists = ifNotExists;
+    }
+
+    public void setSelectSQL(String selectSQL) {
+        this.selectSQL = selectSQL;
+    }
+
+    public void setColumnNames(String[] cols) {
+        this.columnNames = cols;
+    }
+
+    public void setComment(String comment) {
+        this.comment = comment;
+    }
+
+    public void setOrReplace(boolean orReplace) {
+        this.orReplace = orReplace;
+    }
+
+    public void setForce(boolean force) {
+        this.force = force;
+    }
+
+
     public int update() {
         session.commit(true);
         Database db = session.getDatabase();
-        if (getSchema().findTableOrView(session, viewName) != null) {
+        Table existingView = getSchema().findTableOrView(session, viewName);
+
+        List<DependentView> dependentViewSql = new ArrayList<DependentView>();
+
+        if (existingView != null) {
             if (ifNotExists) {
                 return 0;
             }
-            throw DbException.get(ErrorCode.VIEW_ALREADY_EXISTS_1, viewName);
+
+            if (orReplace && existingView.getTableType().equals(Table.VIEW)) {
+                db.renameSchemaObject(session, existingView, db.getTempTableName(session));
+                loadDependentViewSql(existingView, dependentViewSql);
+            } else {
+                throw DbException.get(ErrorCode.VIEW_ALREADY_EXISTS_1, viewName);
+            }
         }
         int id = getObjectId();
         String querySQL;
@@ -77,23 +120,73 @@ public class CreateView extends SchemaCommand {
             // this is not strictly required - ignore exceptions, specially when using FORCE
         }
         db.addSchemaObject(session, view);
+
+        if (existingView != null) {
+            recreateDependentViews(db, existingView, dependentViewSql, view);
+        }
         return 0;
     }
 
-    public void setIfNotExists(boolean ifNotExists) {
-        this.ifNotExists = ifNotExists;
-    }
 
-    public void setSelectSQL(String selectSQL) {
-        this.selectSQL = selectSQL;
+    private void recreateDependentViews(Database db, Table existingView, List<DependentView> dependentViewSql, TableView view) {
+        String failedView = null;
+        try {
+            // recreate the dependent views
+            for (DependentView dependentView : dependentViewSql) {
+                failedView = dependentView.viewName;
+                if (force) {
+                    execute(dependentView.createForceSql, true);
+                } else {
+                    execute(dependentView.createSql, true);
+                }
+            }
+            // Delete the original view
+            db.removeSchemaObject(session, existingView);
+
+        } catch (DbException e) {
+            db.removeSchemaObject(session, view);
+
+            // Put back the old view
+            db.renameSchemaObject(session, existingView, viewName);
+
+            // Try to put back the dependent views
+            for (DependentView dependentView : dependentViewSql) {
+                execute(dependentView.createForceSql, true);
+            }
+
+            throw DbException.get(ErrorCode.CANNOT_DROP_2, e, existingView.getName(), failedView);
+        }
     }
 
-    public void setColumnNames(String[] cols) {
-        this.columnNames = cols;
+    private void loadDependentViewSql(DbObject tableOrView, List<DependentView> recreate) {
+        for (DbObject view : tableOrView.getChildren()) {
+            if (view instanceof TableView) {
+                recreate.add(new DependentView((TableView) view));
+                loadDependentViewSql(view, recreate);
+            }
+        }
     }
 
-    public void setComment(String comment) {
-        this.comment = comment;
+    // Class that holds a snapshot of dependent view information.
+    // We can't just work with TableViews directly because they become invalid
+    // when we drop the parent view.
+    private class DependentView {
+        String viewName;
+        String createSql;
+        String createForceSql;
+
+        private DependentView(TableView view) {
+            this.viewName = view.getName();
+            this.createSql = view.getCreateSQL(true, false);
+            this.createForceSql = view.getCreateSQL(true, true);
+        }
     }
 
+    private void execute(String sql, boolean ddl) {
+        Prepared command = session.prepare(sql);
+        command.update();
+        if (ddl) {
+            session.commit(true);
+        }
+    }
 }

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

@@ -7,11 +7,14 @@
 package org.h2.command.ddl;
 
 import org.h2.constant.ErrorCode;
+import org.h2.constraint.ConstraintReferential;
+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
@@ -21,6 +24,7 @@ public class DropView extends SchemaCommand {
 
     private String viewName;
     private boolean ifExists;
+    private int dropAction = ConstraintReferential.RESTRICT;
 
     public DropView(Session session, Schema schema) {
         super(session, schema);
@@ -30,6 +34,10 @@ public class DropView extends SchemaCommand {
         ifExists = b;
     }
 
+    public void setDropAction(int dropAction) {
+        this.dropAction = dropAction;
+    }
+
     public void setViewName(String viewName) {
         this.viewName = viewName;
     }
@@ -46,6 +54,15 @@ public class DropView extends SchemaCommand {
                 throw DbException.get(ErrorCode.VIEW_NOT_FOUND_1, viewName);
             }
             session.getUser().checkRight(view, Right.ALL);
+
+            if (dropAction == ConstraintReferential.RESTRICT) {
+                for (DbObject child : view.getChildren()) {
+                    if (child instanceof TableView) {
+                        throw DbException.get(ErrorCode.CANNOT_DROP_2, viewName, child.getName());
+                    }
+                }
+            }
+
             view.lock(session, true, true);
             session.getDatabase().removeSchemaObject(session, view);
         }

h2/src/main/org/h2/res/help.csv

@@ -253,7 +253,7 @@ DROP USER [ IF EXISTS ] userName
 ","
 Drops a user."
 "Commands (DDL)","DROP VIEW","
-DROP VIEW [ IF EXISTS ] viewName [RESTRICT | CASCADE ]
+DROP VIEW [ IF EXISTS ] viewName [ RESTRICT | CASCADE ]
 ","
 Drops a view, and all dependent views if the CASCADE clause is used."
 "Commands (DDL)","TRUNCATE TABLE","

h2/src/main/org/h2/table/TableView.java

@@ -152,11 +152,31 @@ public class TableView extends Table {
     }
 
     public String getDropSQL() {
-        return "DROP VIEW IF EXISTS " + getSQL();
+       return getDropSQL(false);
+    }
+
+    public String getDropSQL(boolean cascade) {
+        StatementBuilder buff = new StatementBuilder("DROP VIEW IF EXISTS ");
+        buff.append(getSQL());
+        if (cascade) {
+            buff.append(" CASCADE");
+        }
+        return buff.toString();
     }
 
     public String getCreateSQL() {
-        StatementBuilder buff = new StatementBuilder("CREATE FORCE VIEW ");
+        return getCreateSQL(false, true);
+    }
+
+    public String getCreateSQL(boolean orReplace, boolean force) {
+        StatementBuilder buff = new StatementBuilder("CREATE ");
+        if (orReplace) {
+            buff.append("OR REPLACE ");
+        }
+        if (force) {
+            buff.append("FORCE ");
+        }
+        buff.append("VIEW ");
         buff.append(getSQL());
         if (comment != null) {
             buff.append(" COMMENT ").append(StringUtils.quoteStringSQL(comment));

h2/src/test/org/h2/test/TestAll.java

@@ -60,6 +60,7 @@ import org.h2.test.db.TestTriggersConstraints;
 import org.h2.test.db.TestTwoPhaseCommit;
 import org.h2.test.db.TestView;
 import org.h2.test.db.TestViewAlterTable;
+import org.h2.test.db.TestViewDropView;
 import org.h2.test.jaqu.AliasMapTest;
 import org.h2.test.jaqu.SamplesTest;
 import org.h2.test.jaqu.UpdateTest;
@@ -538,6 +539,7 @@ kill -9 `jps -l | grep "org.h2.test." | cut -d " " -f 1`
         new TestTwoPhaseCommit().runTest(this);
         new TestView().runTest(this);
         new TestViewAlterTable().runTest(this);
+        new TestViewDropView().runTest(this);
 
         // jaqu
         new AliasMapTest().runTest(this);

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

+/*
+ * Copyright 2004-2010 H2 Group. Multiple-Licensed under the H2 License,
+ * Version 1.0, and under the Eclipse Public License, Version 1.0
+ * (http://h2database.com/html/license.html).
+ * Initial Developer: H2 Group
+ */
+package org.h2.test.db;
+
+import org.h2.constant.ErrorCode;
+import org.h2.test.TestBase;
+
+import java.sql.Connection;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+import java.sql.Statement;
+
+/**
+ * Test the impact of DROP VIEW statements on dependent views.
+ */
+public class TestViewDropView extends TestBase {
+
+    private Connection conn;
+    private Statement stat;
+
+    /**
+     * Run just this test.
+     *
+     * @param a ignored
+     */
+    public static void main(String... a) throws Exception {
+        TestBase.createCaller().init().test();
+    }
+
+    public void test() throws Exception {
+        deleteDb("alter");
+        conn = getConnection("alter");
+        stat = conn.createStatement();
+
+        testDropViewDefaultBehaviour();
+        testDropViewRestrict();
+        testDropViewCascade();
+        testCreateOrReplaceView();
+        testCreateOrReplaceViewWithNowInvalidDependentViews();
+        testCreateOrReplaceForceViewWithNowInvalidDependentViews();
+
+        conn.close();
+        deleteDb("alter");
+    }
+
+    private void testDropViewDefaultBehaviour() throws SQLException {
+        createTestData();
+
+        try {
+            stat.execute("drop view v1"); // Should fail because have dependencies
+        } catch (SQLException e) {
+            assertEquals(ErrorCode.CANNOT_DROP_2, e.getErrorCode());
+        }
+
+        checkViewRemainsValid();
+    }
+
+    private void testDropViewRestrict() throws SQLException {
+        createTestData();
+
+        try {
+            stat.execute("drop view v1 restrict"); // Should fail because have dependencies
+        } catch (SQLException e) {
+            assertEquals(ErrorCode.CANNOT_DROP_2, e.getErrorCode());
+        }
+
+        checkViewRemainsValid();
+    }
+
+    private void testDropViewCascade() throws SQLException {
+        createTestData();
+
+        stat.execute("drop view v1 cascade");
+
+        try {
+            stat.execute("select * from v1");
+            fail("Exception should be thrown - v1 should be deleted");
+        } catch (SQLException e) {
+            assertEquals(ErrorCode.TABLE_OR_VIEW_NOT_FOUND_1, e.getErrorCode());
+        }
+
+        try {
+            stat.execute("select * from v2");
+            fail("Exception should be thrown - v2 should be deleted");
+        } catch (SQLException e) {
+            assertEquals(ErrorCode.TABLE_OR_VIEW_NOT_FOUND_1, e.getErrorCode());
+        }
+
+        try {
+            stat.execute("select * from v3");
+            fail("Exception should be thrown - v3 should be deleted");
+        } catch (SQLException e) {
+            assertEquals(ErrorCode.TABLE_OR_VIEW_NOT_FOUND_1, e.getErrorCode());
+        }
+
+        stat.execute("drop table test");
+    }
+
+    private void testCreateOrReplaceView() throws SQLException {
+        createTestData();
+
+        stat.execute("create or replace view v1 as select a as b, b as a, c from test");
+
+        checkViewRemainsValid();
+    }
+
+    private void testCreateOrReplaceViewWithNowInvalidDependentViews() throws SQLException {
+        createTestData();
+
+        try {
+            // v2 and v3 need more than just "c", so we should get an error
+            stat.execute("create or replace view v1 as select c from test");
+            fail("Exception should be thrown - dependent views need more columns than just 'c'");
+        } catch (SQLException e) {
+            assertEquals(ErrorCode.CANNOT_DROP_2, e.getErrorCode());
+        }
+
+        // Make sure our old views come back ok
+        checkViewRemainsValid();
+    }
+
+    private void testCreateOrReplaceForceViewWithNowInvalidDependentViews() throws SQLException {
+        createTestData();
+
+        // v2 and v3 need more than just "c", but we want to force the creation of v1 anyway
+        stat.execute("create or replace force view v1 as select c from test");
+
+        try {
+            // now v2 and v3 are broken, but they still exist -- if there is any value to that...?
+            ResultSet rs = stat.executeQuery("select b from v2");
+            assertTrue(rs.next());
+            assertEquals(1, rs.getInt(1));
+            assertFalse(rs.next());
+
+        } catch (SQLException e) {
+            assertEquals(ErrorCode.COLUMN_NOT_FOUND_1, e.getErrorCode());
+        }
+
+        stat.execute("drop table test");
+    }
+
+    private void createTestData() throws SQLException {
+        stat.execute("create table test(a int, b int, c int)");
+        stat.execute("insert into test(a, b, c) values (1, 2, 3)");
+        stat.execute("create view v1 as select a as b, b as a from test");
+        // child of v1
+        stat.execute("create view v2 as select * from v1");
+        // child of v2
+        stat.execute("create view v3 as select * from v2");
+    }
+
+    private void checkViewRemainsValid() throws SQLException {
+        ResultSet rs = stat.executeQuery("select b from v1");
+        assertTrue(rs.next());
+        assertEquals(1, rs.getInt(1));
+        assertFalse(rs.next());
+
+        rs = stat.executeQuery("select b from v2");
+        assertTrue(rs.next());
+        assertEquals(1, rs.getInt(1));
+        assertFalse(rs.next());
+
+        rs = stat.executeQuery("select b from test");
+        assertTrue(rs.next());
+        assertEquals(2, rs.getInt(1));
+        assertFalse(rs.next());
+
+        stat.execute("drop table test");
+
+        ResultSet d = conn.getMetaData().getTables(null, null, null, null);
+        while (d.next()) {
+            if (!d.getString(2).equals("INFORMATION_SCHEMA")) {
+                fail("Should have no tables left in the database, not: " + d.getString(2) + "." + d.getString(3));
+            }
+        }
+    }
+}

h2/src/test/org/h2/test/test-1.2.txt

@@ -5983,6 +5983,9 @@ SELECT * FROM CHILDREN_CLASS12;
 > rows: 4
 
 DROP VIEW CHILDREN_CLASS1;
+> exception
+
+DROP VIEW CHILDREN_CLASS1 CASCADE;
 > ok
 
 DROP VIEW CHILDREN_CLASS2;