MySQL查询和EXISTS子句

Question

我需要返回operacao='DELETE'如果它存在，或者如果它不存在，则返回它现在返回的相同内容。现在查询返回找到的第一个'operacao'。

让我们说我需要知道operacao也存在'DELETE'。

SELECT A.*, wf.RHID as rhidwf, wf.operacao as operacao  
from (
  SELECT 
    CONCAT(RHID) AS pk, RHID, CD_DOC_ID, SEQ, NR_DOCUMENTO, EMISSOR,
    DT_EMISSAO, DT_VALIDADE 
  FROM rh_id_documentos   
  WHERE RHID='6' AND CD_DOC_ID='1' AND SEQ='1') A 
LEFT JOIN fo_on_workflow wf  ON A.pk = wf.RHID 
GROUP BY  A.RHID, A.CD_DOC_ID, A.SEQ;

Answer 1

(define high
  (λ (start stop)
    (cond
      [(> start stop) '()]
      [else (cons start (high (add1 start) stop))])))