Add checking for creating the same database. (#7028)

shardingsphere-db-protocol/shardingsphere-db-protocol-mysql/src/main/java/org/apache/shardingsphere/db/protocol/mysql/constant/MySQLServerErrorCode.java

@@ -42,6 +42,8 @@ public enum MySQLServerErrorCode implements SQLErrorCode {
     
     ER_UNSUPPORTED_PS(1295, "HY000", "This command is not supported in the prepared statement protocol yet"),
     
+    ER_DB_CREATE_EXISTS(1007, "HY000", "Message: Can't create database '%s'; database exists"),
+    
     ER_ERROR_ON_MODIFYING_GTID_EXECUTED_TABLE(3176, "HY000", 
             "Please do not modify the %s table with an XA transaction. This is an internal system table used to store GTIDs for committed transactions. " 
                     + "Although modifying it can lead to an inconsistent GTID state, if neccessary you can modify it with a non-XA transaction.");

shardingsphere-proxy/shardingsphere-proxy-backend/src/main/java/org/apache/shardingsphere/proxy/backend/exception/DBCreateExistsException.java

+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.shardingsphere.proxy.backend.exception;
+
+import lombok.Getter;
+import lombok.RequiredArgsConstructor;
+
+/**
+ * DB create exists exception.
+ */
+@RequiredArgsConstructor
+@Getter
+public final class DBCreateExistsException extends BackendException {
+    
+    private static final long serialVersionUID = 779787160167652641L;
+    
+    private final String databaseName;
+}

shardingsphere-proxy/shardingsphere-proxy-backend/src/main/java/org/apache/shardingsphere/proxy/backend/text/admin/RDLBackendHandler.java

@@ -27,6 +27,7 @@ import org.apache.shardingsphere.infra.database.type.DatabaseType;
 import org.apache.shardingsphere.infra.yaml.swapper.YamlRuleConfigurationSwapperEngine;
 import org.apache.shardingsphere.kernel.context.StandardSchemaContexts;
 import org.apache.shardingsphere.proxy.backend.communication.jdbc.connection.BackendConnection;
+import org.apache.shardingsphere.proxy.backend.exception.DBCreateExistsException;
 import org.apache.shardingsphere.proxy.backend.response.BackendResponse;
 import org.apache.shardingsphere.proxy.backend.response.error.ErrorResponse;
 import org.apache.shardingsphere.proxy.backend.response.query.QueryData;
@@ -72,7 +73,10 @@ public final class RDLBackendHandler implements TextProtocolBackendHandler {
     }
     
     private BackendResponse execute(final CreateDatabaseStatementContext context) {
-        SchemaNameCallback.getInstance().run(context.getSqlStatement().getSchemaName(), true);
+        if (ProxySchemaContexts.getInstance().getSchemaNames().contains(context.getSqlStatement().getDatabaseName())) {
+            return new ErrorResponse(new DBCreateExistsException(context.getSqlStatement().getDatabaseName()));
+        }
+        SchemaNameCallback.getInstance().run(context.getSqlStatement().getDatabaseName(), true);
         // TODO Need to get the executed feedback from registry center for returning.
         UpdateResponse result = new UpdateResponse();
         result.setType("CREATE");

shardingsphere-proxy/shardingsphere-proxy-backend/src/test/java/org/apache/shardingsphere/proxy/backend/communication/jdbc/execute/OrchestrationSchemaContextsFixture.java

@@ -41,7 +41,7 @@ public final class OrchestrationSchemaContextsFixture implements SchemaContexts
     
     @Override
     public Map<String, SchemaContext> getSchemaContexts() {
-        return Collections.emptyMap();
+        return Collections.singletonMap("schema", mock(SchemaContext.class));
     }
     
     @Override

shardingsphere-proxy/shardingsphere-proxy-backend/src/test/java/org/apache/shardingsphere/proxy/backend/text/admin/RDLBackendHandlerTest.java

@@ -25,6 +25,7 @@ import org.apache.shardingsphere.kernel.context.SchemaContext;
 import org.apache.shardingsphere.kernel.context.StandardSchemaContexts;
 import org.apache.shardingsphere.proxy.backend.communication.jdbc.connection.BackendConnection;
 import org.apache.shardingsphere.proxy.backend.communication.jdbc.execute.OrchestrationSchemaContextsFixture;
+import org.apache.shardingsphere.proxy.backend.exception.DBCreateExistsException;
 import org.apache.shardingsphere.proxy.backend.response.BackendResponse;
 import org.apache.shardingsphere.proxy.backend.response.error.ErrorResponse;
 import org.apache.shardingsphere.proxy.backend.response.update.UpdateResponse;
@@ -69,6 +70,19 @@ public final class RDLBackendHandlerTest {
         assertThat(response, instanceOf(UpdateResponse.class));
     }
     
+    @Test
+    public void assertExecuteCreateDatabaseContextWithException() {
+        BackendConnection connection = mock(BackendConnection.class);
+        when(connection.getSchema()).thenReturn("schema");
+        RDLBackendHandler executeEngine = new RDLBackendHandler(connection, new CreateDatabaseStatement("schema"));
+        BackendResponse response = executeEngine.execute();
+        assertThat(response, instanceOf(ErrorResponse.class));
+        setOrchestrationSchemaContexts(true);
+        response = executeEngine.execute();
+        assertThat(response, instanceOf(ErrorResponse.class));
+        assertThat(((ErrorResponse) response).getCause(), instanceOf(DBCreateExistsException.class));
+    }
+    
     private Map<String, SchemaContext> getSchemaContextMap() {
         SchemaContext result = new SchemaContext("schema", null, null);
         return Collections.singletonMap("schema", result);
@@ -103,7 +117,7 @@ public final class RDLBackendHandlerTest {
         Field schemaContexts = ProxySchemaContexts.getInstance().getClass().getDeclaredField("schemaContexts");
         schemaContexts.setAccessible(true);
         if (isOrchestration) {
-            schemaContexts.set(ProxySchemaContexts.getInstance(), mock(OrchestrationSchemaContextsFixture.class));
+            schemaContexts.set(ProxySchemaContexts.getInstance(), new OrchestrationSchemaContextsFixture());
         } else {
             schemaContexts.set(ProxySchemaContexts.getInstance(), new StandardSchemaContexts());
         }

shardingsphere-proxy/shardingsphere-proxy-frontend/shardingsphere-proxy-frontend-mysql/src/main/java/org/apache/shardingsphere/proxy/frontend/mysql/MySQLErrPacketFactory.java

@@ -22,6 +22,7 @@ import lombok.NoArgsConstructor;
 import org.apache.shardingsphere.db.protocol.error.CommonErrorCode;
 import org.apache.shardingsphere.db.protocol.mysql.constant.MySQLServerErrorCode;
 import org.apache.shardingsphere.db.protocol.mysql.packet.generic.MySQLErrPacket;
+import org.apache.shardingsphere.proxy.backend.exception.DBCreateExistsException;
 import org.apache.shardingsphere.proxy.backend.exception.NoDatabaseSelectedException;
 import org.apache.shardingsphere.proxy.backend.exception.TableModifyInTransactionException;
 import org.apache.shardingsphere.proxy.backend.exception.UnknownDatabaseException;
@@ -62,6 +63,9 @@ public final class MySQLErrPacketFactory {
         if (cause instanceof NoDatabaseSelectedException) {
             return new MySQLErrPacket(sequenceId, MySQLServerErrorCode.ER_NO_DB_ERROR);
         }
+        if (cause instanceof DBCreateExistsException) {
+            return new MySQLErrPacket(sequenceId, MySQLServerErrorCode.ER_DB_CREATE_EXISTS, ((DBCreateExistsException) cause).getDatabaseName());
+        }
         return new MySQLErrPacket(sequenceId, CommonErrorCode.UNKNOWN_EXCEPTION, cause.getMessage());
     }
 }

shardingsphere-sql-parser/shardingsphere-sql-parser-statement/src/main/java/org/apache/shardingsphere/sql/parser/sql/statement/ddl/CreateDatabaseStatement.java

@@ -27,5 +27,5 @@ import lombok.RequiredArgsConstructor;
 @Getter
 public final class CreateDatabaseStatement extends DDLStatement {
     
-    private final String schemaName;
+    private final String databaseName;
 }