content: /*
   * Copyright (C) 2010-2101 Alibaba Group Holding Limited.
   *
   * Licensed 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 com.alibaba.otter.node.etl.common.db.dialect.mysql;
  
  import com.alibaba.otter.node.etl.common.db.dialect.AbstractSqlTemplate;
  
  /**
   * mysql sql生成模板
   * 
   * @author jianghang 2011-10-27 下午01:41:20
   * @version 4.0.0
   */
  public class MysqlSqlTemplate extends AbstractSqlTemplate {
  
      private static final String ESCAPE = "`";
  
      public String getMergeSql(String schemaName, String tableName, String[] pkNames, String[] columnNames,
                                String[] viewColumnNames, boolean includePks, String shardColumn) {
          StringBuilder sql = new StringBuilder("insert into " + getFullName(schemaName, tableName) + "(");
          int size = columnNames.length;
          for (int i = 0; i < size; i++) {
              sql.append(appendEscape(columnNames[i])).append(" , ");
          }
          size = pkNames.length;
          for (int i = 0; i < size; i++) {
              sql.append(appendEscape(pkNames[i])).append((i + 1 < size) ? " , " : "");
          }
  
          sql.append(") values (");
          size = columnNames.length;
          for (int i = 0; i < size; i++) {
              sql.append("?").append(" , ");
          }
          size = pkNames.length;
          for (int i = 0; i < size; i++) {
              sql.append("?").append((i + 1 < size) ? " , " : "");
          }
          sql.append(")");
          sql.append(" on duplicate key update ");
  
          size = columnNames.length;
          for (int i = 0; i < size; i++) {
              // 如果是DRDS数据库, 并且存在拆分键 且 等于当前循环列, 跳过
              if(!includePks && shardColumn != null && columnNames[i].equals(shardColumn)){
                  continue;
              }
  
              sql.append(appendEscape(columnNames[i]))
                  .append("=values(")
                  .append(appendEscape(columnNames[i]))
                  .append(")");
              if (includePks) {
                  sql.append(" , ");
              } else {
                  sql.append((i + 1 < size) ? " , " : "");
              }
          }
  
          if (includePks) {
              // mysql merge sql匹配了uniqe / primary key时都会执行update，所以需要更新pk信息
              size = pkNames.length;
              for (int i = 0; i < size; i++) {
                  sql.append(appendEscape(pkNames[i])).append("=values(").append(appendEscape(pkNames[i])).append(")");
                  sql.append((i + 1 < size) ? " , " : "");
              }
          }
  
          return sql.toString().intern();// intern优化，避免出现大量相同的字符串
      }
  
      protected String appendEscape(String columnName) {
          return ESCAPE + columnName + ESCAPE;
      }
  
  }
  