private void parseRegularJoin(JoinRelation relation, Map<String, Node> nodeMap,
            Map<String, String> tableNameAliasMap, Map<String, List<FilterFunction>> conditionMap, StringBuilder sb) {
        for (int i = 1; i < relation.getInputs().size(); i++) {
            String inputId = relation.getInputs().get(i);
            sb.append("\n      ").append(relation.format()).append(" ")
                    .append(nodeMap.get(inputId).genTableName()).append(" ")
                    .append(tableNameAliasMap.get(inputId)).append("\n    ON ");
            parseJoinConditions(inputId, conditionMap, tableNameAliasMap, sb);
        }
    }
Generate select sql for union

@param fieldRelations The relation of fieds
@param unionRelation The union relation of sql
@param nodeMap Store the mapping relation between node id and node
@return Transform sql for this node logic
inlong-sort/sort-core/src/main/java/org/apache/inlong/sort/parser/impl/FlinkSqlParser.java