解码返回多行

Question

我有一个商业案例，在表格中我可能有特定的价值，或者它的价值为＆＃39; ALL＆＃39;。当我查询表格时，如果特定输入匹配，我需要该特定记录。如果它不匹配则应考虑并返回ALL的条目。

以下是您尝试复制问题的案例。

CREATE TABLE lookup_value (
 country             VARCHAR2(2) NOT NULL,
 department               VARCHAR2(30) NOT NULL,
 problem_code     VARCHAR2(30),
 disposition                 VARCHAR2(30));

INSERT INTO lookup_value VALUES ('US','SALES','P0044','EXCHANGE')

INSERT INTO lookup_value VALUES ('US','SALES','ALL','EXCHANGE')

INSERT INTO lookup_value VALUES ('US','SALES','P0020','ALL')

INSERT INTO lookup_value VALUES ('US','SALES','ALL','ALL')

INSERT INTO lookup_value VALUES ('US','OPERATIONS','P0044','ACKNOELEDGE')

INSERT INTO lookup_value VALUES ('US','OPERATIONS','ALL', 'ALL')


SELECT *
  FROM lookup_value
 WHERE country = 'US'
   AND department = 'SALES'
   AND problem_code = DECODE (:problem, problem_code, :problem, 'ALL')
   AND disposition = DECODE (:disp, disposition, :disp, 'ALL')

如果我运行上面的查询，传递problem_code = P0044和disposition =＆＃39; EXCHANGE＆＃39;，它会返回3行，因为我只需要一行。

COUNTRY DEPARTMENT  PROBLEM_CODE    DISPOSITION
-----------------------------------------------------------
US  SALES   P0044   EXCHANGE
US  SALES   ALL EXCHANGE
US  SALES   ALL ALL

此致 Tauseef