content: /*
   * Copyright (C) 2016-2023 ActionTech.
   * based on code by MyCATCopyrightHolder Copyright (c) 2013, OpenCloudDB/MyCAT.
   * License: http://www.gnu.org/licenses/gpl.html GPL version 2 or higher.
   */
  package com.actiontech.dble.services.manager.handler;
  
  import com.actiontech.dble.DbleServer;
  import com.actiontech.dble.config.ErrorCode;
  import com.actiontech.dble.net.mysql.OkPacket;
  import com.actiontech.dble.services.manager.ManagerService;
  import com.actiontech.dble.services.manager.information.ManagerSchemaInfo;
  import com.actiontech.dble.util.StringUtil;
  
  /**
   * @author mycat
   */
  public final class UseHandler {
      private UseHandler() {
      }
  
      public static void handle(String sql, ManagerService service, int offset) {
          String schema = sql.substring(offset).trim();
          int length = schema.length();
          if (length > 0) {
              if (schema.endsWith(";")) {
                  schema = schema.substring(0, schema.length() - 1);
              }
              schema = StringUtil.replaceChars(schema, "`", null);
              length = schema.length();
              if (schema.charAt(0) == '\'' && schema.charAt(length - 1) == '\'') {
                  schema = schema.substring(1, length - 1);
              }
              if (DbleServer.getInstance().getSystemVariables().isLowerCaseTableNames()) {
                  schema = schema.toLowerCase();
              }
          }
          if (!ManagerSchemaInfo.SCHEMA_NAME.equals(schema)) {
              service.writeErrMessage(ErrorCode.ER_BAD_DB_ERROR, "Unknown database '" + schema + "'");
              return;
          }
          service.setSchema(schema);
          OkPacket okPacket = OkPacket.getDefault();
          okPacket.write(service.getConnection());
      }
  
  }
  