如果在Where子句中的语句

Question

我正在使用包含“WHERE”子句中的“IF”语句的查询。但PL \ SQL Developer在执行时会出现一些错误。任何人都可以请帮助我正确的查询？以下是查询：

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; 

我收到错误“ORA-00920：invalid relational operator”。

配售括号status_flag = STATUS_ACTIVE导致错误“ORA-00907：缺少右括号”

Answer 1

案件可能帮助你：

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评估多条件下产生一个值。因此，在第一次使用时，我检查status_flag的值，根据它的值是什么返回'A'，'T'或null，并将其与t.status进行比较。我用第二个CASE语句为business_unit列做同样的事情。

Answer 2

IF一样，你不能使用。你可以做你想做与AND和OR什么：

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;