我正在嘗試使用 JOOQ 以編程方式在 Java 中構建以下查詢： select emisor,       anio,       mes,       sum(case when codigo = '01' then total else 0 end) as facturas,       sum(case when codigo = '03' then total else 0 end) as boletas,       sum(case when codigo = '07' then total else 0 end) as notas_credito,       sum(case when codigo = '08' then total else 0 end) as notas_debito,       sum(case when codigo = 'RC' then total else 0 end) as resumenes,       sum(case when codigo = 'RA' then total else 0 end) as anulaciones,       sum(case when codigo = '40' then total else 0 end) as percepciones,       sum(case when codigo = '20' then total else 0 end) as retenciones,       sum(case when codigo = 'RV' then total else 0 end) as reversiones,       sum(case when codigo = '09' then total else 0 end) as guiasfrom (select ruc_emisor                      as emisor,             year(fec_registro)              as anio,             month(fec_registro)             as mes,             substring(nom_solicitud, 13, 2) as codigo,             count(*)                        as total      from bd_ose.tx_solicitud      where year(fec_registro) = '2019'        and month(fec_registro) = 7      group by ruc_emisor, anio, mes, codigo      UNION      select num_ruc             as emisor,             year(fec_registro)  as anio,             month(fec_registro) as mes,             cod_cpe             as codigo,             count(*)            as total      from bd_ose.tx_comprobante_inf      where year(fec_registro) = '2019'        and month(fec_registro) = 7      group by num_ruc, anio, mes, codigo     ) solicitudesgroup by emisor, anio, mesorder by emisor;在 SQL 和 JOOQ 方面，我仍然相當缺乏經驗，但我決定從內部開始，逐步解決問題。當我嘗試將 .union() 方法應用于兩個內部子查詢時，我遇到了問題。我的 IDE 突出顯示了一個類型不匹配錯誤，指出 union 需要一個類型為“org.jooq.Select<...”的參數，而我提供的參數類型為“org.jooq.SelectHavingStep<... " - 這是從 .groupBy() 返回的類型我已經檢查了 [union docs] ( https://www.jooq.org/doc/3.11/manual/sql-building/sql-statements/select-statement/union-clause/ )的文檔并嘗試尋找類似的其他地方的案例，但不幸的是還沒有成功。