如果在Where子句中的語句

Question

我正在使用包含「WHERE」子句中的「IF」語句的查詢。但PL \ SQL Developer在執行時會出現一些錯誤。任何人都可以請幫助我正確的查詢？以下是查詢：

SELECT t.first_name, 
     t.last_name, 
     t.employid, 
     t.status 
    FROM employeetable t 
WHERE IF status_flag = STATUS_ACTIVE then t.status = 'A' 
     IF status_flag = STATUS_INACTIVE then t.status = 'T' 
     IF source_flag = SOURCE_FUNCTION then t.business_unit = 'production' 
     IF source_flag = SOURCE_USER then t.business_unit = 'users' 
    AND t.first_name LIKE firstname 
    AND t.last_name LIKE lastname 
    AND t.employid LIKE employeeid; 

我收到錯誤「ORA-00920：invalid relational operator」。

配售括號status_flag = STATUS_ACTIVE導致錯誤「ORA-00907：缺少右括號」

Answer 1

案件可能幫助你：

SELECT t.first_name, 
     t.last_name, 
     t.employid, 
     t.status 
    FROM employeetable t 
WHERE t.status = (CASE WHEN status_flag = STATUS_ACTIVE THEN 'A' 
         WHEN status_flag = STATUS_INACTIVE THEN 'T' 
         ELSE null END) 
    AND t.business_unit = (CASE WHEN source_flag = SOURCE_FUNCTION THEN 'production' 
           WHEN source_flag = SOURCE_USER THEN 'users' 
           ELSE null END) 
    AND t.first_name LIKE firstname 
    AND t.last_name LIKE lastname 
    AND t.employid LIKE employeeid; 

的CASE statement評估多條件下產生一個值。因此，在第一次使用時，我檢查status_flag的值，根據它的值是什麼返回'A'，'T'或null，並將其與t.status進行比較。我用第二個CASE語句爲business_unit列做同樣的事情。

Answer 2

IF一樣，你不能使用。你可以做你想做與AND和OR什麼：

SELECT t.first_name, 
     t.last_name, 
     t.employid, 
     t.status 
    FROM employeetable t 
WHERE (status_flag = STATUS_ACTIVE AND t.status = 'A' 
    OR status_flag = STATUS_INACTIVE AND t.status = 'T' 
    OR source_flag = SOURCE_FUNCTION AND t.business_unit = 'production' 
    OR source_flag = SOURCE_USER  AND t.business_unit = 'users') 
    AND t.first_name LIKE firstname 
    AND t.last_name LIKE lastname 
    AND t.employid LIKE employeeid;