Merge pull request #720 from ilm-informatique/dropTableRestrict

DROP TABLE RESTRICT shouldn't drop foreign keys in other tables

h2/src/docsrc/help/help.csv

@@ -907,8 +907,8 @@ DROP SEQUENCE SEQ_ID
 DROP TABLE [ IF EXISTS ] tableName [,...] [ RESTRICT | CASCADE ]
 ","
 Drops an existing table, or a list of tables.
-The command will fail if dependent views exist and the RESTRICT clause is used (the default).
-All dependent views are dropped as well if the CASCADE clause is used.
+The command will fail if dependent objects exist and the RESTRICT clause is used (the default).
+All dependent views and constraints are dropped as well if the CASCADE clause is used.
 This command commits an open transaction in this connection.
 ","
 DROP TABLE TEST

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

@@ -5,9 +5,12 @@
  */
 package org.h2.command.ddl;
 
+import java.util.List;
 import java.util.concurrent.CopyOnWriteArrayList;
+
 import org.h2.api.ErrorCode;
 import org.h2.command.CommandInterface;
+import org.h2.constraint.Constraint;
 import org.h2.constraint.ConstraintReferential;
 import org.h2.engine.Database;
 import org.h2.engine.Right;
@@ -73,15 +76,29 @@ public class DropTable extends SchemaCommand {
                 throw DbException.get(ErrorCode.CANNOT_DROP_TABLE_1, tableName);
             }
             if (dropAction == ConstraintReferential.RESTRICT) {
+                StatementBuilder buff = new StatementBuilder();
                 CopyOnWriteArrayList<TableView> dependentViews = table.getDependentViews();
                 if (dependentViews != null && dependentViews.size() > 0) {
-                    StatementBuilder buff = new StatementBuilder();
                     for (TableView v : dependentViews) {
                         buff.appendExceptFirst(", ");
                         buff.append(v.getName());
                     }
-                    throw DbException.get(ErrorCode.CANNOT_DROP_2, tableName, buff.toString());
                 }
+                if (session.getDatabase()
+                        .getSettings().standardDropTableRestrict) {
+                    final List<Constraint> constraints = table.getConstraints();
+                    if (constraints != null && constraints.size() > 0) {
+                        for (Constraint c : constraints) {
+                            if (c.getTable() != table) {
+                                buff.appendExceptFirst(", ");
+                                buff.append(c.getName());
+                            }
+                        }
+                    }
+                }
+                if (buff.length() > 0)
+                    throw DbException.get(ErrorCode.CANNOT_DROP_2, tableName, buff.toString());
+
             }
             table.lock(session, true, true);
         }

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

@@ -350,6 +350,17 @@ public class DbSettings extends SettingsBase {
      */
     public final boolean multiThreaded = get("MULTI_THREADED", false);
 
+    /**
+     * Database setting <code>STANDARD_DROP_TABLE_RESTRICT</code> (default:
+     * false).<br />
+     * <code>true</code> if DROP TABLE RESTRICT should fail if there's any
+     * foreign key referencing the table to be dropped. <code>false</code> if
+     * foreign keys referencing the table to be dropped should be silently
+     * dropped as well.
+     */
+    public final boolean standardDropTableRestrict = get(
+            "STANDARD_DROP_TABLE_RESTRICT", false);
+
     private DbSettings(HashMap<String, String> s) {
         super(s);
     }

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

@@ -19,7 +19,6 @@ import java.sql.Timestamp;
 import java.util.List;
 import java.util.Random;
 import java.util.concurrent.TimeUnit;
-
 import org.h2.api.ErrorCode;
 import org.h2.engine.Constants;
 import org.h2.store.fs.FileUtils;
@@ -54,6 +53,7 @@ public class TestCases extends TestBase {
         testGroupSubquery();
         testCountDistinctNotNull();
         testDependencies();
+        testDropTable();
         testConvertType();
         testSortedSelect();
         testMaxMemoryRows();
@@ -150,7 +150,7 @@ public class TestCases extends TestBase {
         stat.execute("alter table b add constraint x " +
                 "foreign key(a_id) references a(id)");
         stat.execute("update a set x=200");
-        stat.execute("drop table if exists a, b");
+        stat.execute("drop table if exists a, b cascade");
         conn.close();
     }
 
@@ -278,6 +278,70 @@ public class TestCases extends TestBase {
         conn.close();
     }
 
+    private void testDropTable() throws SQLException {
+        trace("testDropTable");
+        final boolean[] booleans = new boolean[] { true, false };
+        for (final boolean stdDropTableRestrict : booleans) {
+            for (final boolean restrict : booleans) {
+                testDropTableNoReference(stdDropTableRestrict, restrict);
+                testDropTableViewReference(stdDropTableRestrict, restrict);
+                testDropTableForeignKeyReference(stdDropTableRestrict, restrict);
+            }
+        }
+    }
+
+    private Statement createTable(final boolean stdDropTableRestrict) throws SQLException {
+        deleteDb("cases");
+        Connection conn = getConnection("cases;STANDARD_DROP_TABLE_RESTRICT=" + stdDropTableRestrict);
+        Statement stat = conn.createStatement();
+        stat.execute("create table test(id int)");
+        return stat;
+    }
+
+    private void dropTable(final boolean restrict, Statement stat, final boolean expectedDropSuccess)
+            throws SQLException {
+        assertThrows(expectedDropSuccess ? 0 : ErrorCode.CANNOT_DROP_2, stat)
+                .execute("drop table test " + (restrict ? "restrict" : "cascade"));
+        assertThrows(expectedDropSuccess ? ErrorCode.TABLE_OR_VIEW_NOT_FOUND_1 : 0, stat).execute("select * from test");
+    }
+
+    private void testDropTableNoReference(final boolean stdDropTableRestrict, final boolean restrict)
+            throws SQLException {
+        Statement stat = createTable(stdDropTableRestrict);
+        // always succeed as there's no reference to the table
+        dropTable(restrict, stat, true);
+        stat.getConnection().close();
+    }
+
+    private void testDropTableViewReference(final boolean stdDropTableRestrict, final boolean restrict)
+            throws SQLException {
+        Statement stat = createTable(stdDropTableRestrict);
+        stat.execute("create view abc as select * from test");
+        // drop allowed only if cascade
+        final boolean expectedDropSuccess = !restrict;
+        dropTable(restrict, stat, expectedDropSuccess);
+        // missing view if the drop succeeded
+        assertThrows(expectedDropSuccess ? ErrorCode.TABLE_OR_VIEW_NOT_FOUND_1 : 0, stat).execute("select * from abc");
+        stat.getConnection().close();
+    }
+
+    private void testDropTableForeignKeyReference(final boolean stdDropTableRestrict, final boolean restrict)
+            throws SQLException {
+        Statement stat = createTable(stdDropTableRestrict);
+        stat.execute("create table ref(id int, id_test int, foreign key (id_test) references test (id)) ");
+        // test table is empty, so the foreign key forces ref table to be also
+        // empty
+        assertThrows(ErrorCode.REFERENTIAL_INTEGRITY_VIOLATED_PARENT_MISSING_1, stat)
+                .execute("insert into ref values(1,2)");
+        // drop allowed if cascade or old style
+        final boolean expectedDropSuccess = !stdDropTableRestrict || !restrict;
+        dropTable(restrict, stat, expectedDropSuccess);
+        // insertion succeeds if the foreign key was dropped
+        assertThrows(expectedDropSuccess ? 0 : ErrorCode.REFERENTIAL_INTEGRITY_VIOLATED_PARENT_MISSING_1, stat)
+                .execute("insert into ref values(1,2)");
+        stat.getConnection().close();
+    }
+
     private void testConvertType() throws SQLException {
         deleteDb("cases");
         Connection conn = getConnection("cases");