private String genUnionSingleSelectSql(String inputId, String tableName, List<FieldInfo> fields,
            Map<String, Map<String, FieldRelation>> fieldRelationMap,
            Map<String, FieldRelation> defaultFieldRelationMap, Node node) {
        StringBuilder sb = new StringBuilder();
        sb.append("SELECT ");
        Map<String, FieldRelation> fieldRelations = fieldRelationMap.get(inputId);
        if (fieldRelations == null) {
            fieldRelations = defaultFieldRelationMap;
        }
        if (node instanceof HbaseLoadNode) {
            HbaseLoadNode hbaseLoadNode = (HbaseLoadNode) node;
            parseHbaseLoadFieldRelation(hbaseLoadNode.getRowKey(), fieldRelations.values(), sb);
        } else {
            parseFieldRelations(fields, fieldRelations, sb);
        }
        sb.append(" FROM `").append(tableName).append("` ");
        return sb.toString();
    }
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