import org.apache.calcite.sql.JoinType; //导入依赖的package包/类
private static JoinRelType convertJoinType(JoinType joinType) {
	switch (joinType) {
		case COMMA:
		case INNER:
		case CROSS:
			return JoinRelType.INNER;
		case FULL:
			return JoinRelType.FULL;
		case LEFT:
			return JoinRelType.LEFT;
		case RIGHT:
			return JoinRelType.RIGHT;
		default:
			throw Util.unexpected(joinType);
	}
}
 

import org.apache.calcite.sql.JoinType; //导入依赖的package包/类
private static JoinRelType convertJoinType(JoinType joinType) {
  switch (joinType) {
  case COMMA:
  case INNER:
  case CROSS:
    return JoinRelType.INNER;
  case FULL:
    return JoinRelType.FULL;
  case LEFT:
    return JoinRelType.LEFT;
  case RIGHT:
    return JoinRelType.RIGHT;
  default:
    throw Util.unexpected(joinType);
  }
}
 

import org.apache.calcite.sql.JoinType; //导入依赖的package包/类
/** @see #dispatch */
public Result visit(Join e) {
  final Result leftResult = visitChild(0, e.getLeft()).resetAlias();
  final Result rightResult = visitChild(1, e.getRight()).resetAlias();
  final Context leftContext = leftResult.qualifiedContext();
  final Context rightContext = rightResult.qualifiedContext();
  SqlNode sqlCondition = null;
  SqlLiteral condType = JoinConditionType.ON.symbol(POS);
  JoinType joinType = joinType(e.getJoinType());
  if (e.getJoinType() == JoinRelType.INNER && e.getCondition().isAlwaysTrue()) {
    joinType = JoinType.COMMA;
    condType = JoinConditionType.NONE.symbol(POS);
  } else {
    sqlCondition = convertConditionToSqlNode(e.getCondition(),
        leftContext,
        rightContext,
        e.getLeft().getRowType().getFieldCount());
  }
  SqlNode join =
      new SqlJoin(POS,
          leftResult.asFrom(),
          SqlLiteral.createBoolean(false, POS),
          joinType.symbol(POS),
          rightResult.asFrom(),
          condType,
          sqlCondition);
  return result(join, leftResult, rightResult);
}