public static String dealDuplicateFieldName(Map<String, String> refFieldMap, String fieldName) {
        String mappingFieldName = fieldName;
        int index = 1;
        while (refFieldMap.containsKey(mappingFieldName)){
            mappingFieldName = suffixWithChar(fieldName, '0', index);
            index++;
        }

        return mappingFieldName;
    }
parse multi join table name, child query RealTabName is null
@param leftJoin
@param aliasAndRealTabName
core/src/main/java/com/dtstack/flink/sql/util/ParseUtils.java