Oracle中的条件更新声明

Question

我在Oracle中构建条件更新语句时遇到问题。对于易懂，我会简化问题，基本上我的更新语句应该是这样的：

UPDATE SAMPLE_TAB1 t 
    SET t.sample_column1 =NVL(t.sample_column1, **SOME LOGIC**); 

的***SOME LOGIC***部分应该是这样的：（请考虑这只是一个伪代码）

IF ((SELECT sample_column2 FROM SAMPLE_TAB2 
     WHERE sample_column2= sample_value2 
     AND sample_column3 = sample_value3)='FALSE' THEN 
    t.sample_column1 =0; 
ELSE 

    t.sample_column1 =(SELECT sample_column1 FROM SAMPLE_TAB3 
         WHERE sample_column4= sample_value4 
         AND sample_column5 = sample_value5) 

END IF; 

任何关于这个问题的想法都会受到欢迎。谢谢。

Answer 1

试试下面的代码

UPDATE SAMPLE_TAB1 t 
    SET t.sample_column1 = (
     case when ((SELECT sample_column2 FROM SAMPLE_TAB2 
          WHERE sample_column2= sample_value2 
          AND sample_column3 = sample_value3) = 'FALSE') 
      then 0 
     else 
      (SELECT sample_column1 FROM SAMPLE_TAB3 
         WHERE sample_column4= sample_value4 
         AND sample_column5 = sample_value5) 
     end 

    ) 
    WHERE t.sample_column1 is not null; 

Answer 2

尝试以下

UPDATE SAMPLE_TAB1 t 
    SET t.sample_column1 = NVL((SELECT sample_column2 FROM ...), 0) 
WHERE t.sample_column1 is not null 
;