content: /*
   * 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.calcite.sql;
  
  /**
   * Enumerates the types of condition in a join expression.
   */
  public enum JoinConditionType implements Symbolizable {
    /**
     * Join clause has no condition, for example "{@code FROM EMP, DEPT}".
     */
    NONE,
  
    /**
     * Join clause has an {@code ON} condition,
     * for example "{@code FROM EMP JOIN DEPT ON EMP.DEPTNO = DEPT.DEPTNO}".
     */
    ON,
  
    /**
     * Join clause has a {@code USING} condition,
     * for example "{@code FROM EMP JOIN DEPT USING (DEPTNO)}".
     */
    USING
  }
  