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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *     http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  
18  package org.apache.shardingsphere.proxy.backend.mysql.handler.admin.executor;
19  
20  import lombok.Getter;
21  import lombok.RequiredArgsConstructor;
22  import org.apache.shardingsphere.db.protocol.constant.DatabaseProtocolServerInfo;
23  import org.apache.shardingsphere.infra.database.core.type.DatabaseType;
24  import org.apache.shardingsphere.infra.executor.sql.execute.result.query.QueryResultMetaData;
25  import org.apache.shardingsphere.infra.executor.sql.execute.result.query.impl.raw.metadata.RawQueryResultColumnMetaData;
26  import org.apache.shardingsphere.infra.executor.sql.execute.result.query.impl.raw.metadata.RawQueryResultMetaData;
27  import org.apache.shardingsphere.infra.merge.result.MergedResult;
28  import org.apache.shardingsphere.infra.merge.result.impl.local.LocalDataMergedResult;
29  import org.apache.shardingsphere.infra.merge.result.impl.local.LocalDataQueryResultRow;
30  import org.apache.shardingsphere.infra.spi.type.typed.TypedSPILoader;
31  import org.apache.shardingsphere.proxy.backend.handler.admin.executor.DatabaseAdminQueryExecutor;
32  import org.apache.shardingsphere.proxy.backend.session.ConnectionSession;
33  import org.apache.shardingsphere.sql.parser.sql.common.segment.dml.item.ExpressionProjectionSegment;
34  import org.apache.shardingsphere.sql.parser.sql.common.statement.dml.SelectStatement;
35  
36  import java.sql.Types;
37  import java.util.Collections;
38  
39  /**
40   * Show version executor.
41   */
42  @RequiredArgsConstructor
43  @Getter
44  public final class ShowVersionExecutor implements DatabaseAdminQueryExecutor {
45      
46      public static final String FUNCTION_NAME = "version()";
47      
48      private final SelectStatement sqlStatement;
49      
50      private MergedResult mergedResult;
51      
52      @Override
53      public void execute(final ConnectionSession connectionSession) {
54          mergedResult = new LocalDataMergedResult(Collections.singleton(new LocalDataQueryResultRow(
55                  DatabaseProtocolServerInfo.getProtocolVersion(connectionSession.getDatabaseName(), TypedSPILoader.getService(DatabaseType.class, "MySQL")))));
56      }
57      
58      @Override
59      public QueryResultMetaData getQueryResultMetaData() {
60          return new RawQueryResultMetaData(Collections.singletonList(new RawQueryResultColumnMetaData("", FUNCTION_NAME, getLabel(), Types.VARCHAR, "VARCHAR", 100, 0)));
61      }
62      
63      private String getLabel() {
64          return sqlStatement.getProjections().getProjections().stream()
65                  .filter(ExpressionProjectionSegment.class::isInstance).findFirst().map(each -> ((ExpressionProjectionSegment) each).getAliasName().orElse(FUNCTION_NAME)).orElse(FUNCTION_NAME);
66      }
67  }