sql - Oracle中的条件更新语句

Question

我在Oracle中构建条件更新语句时遇到问题。为了便于理解，我将简化问题，基本上我的更新语句应如下所示：

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

该***SOME LOGIC***部分应如下所示：（请认为这只是一个伪代码）

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;

欢迎对这个问题提出任何想法。谢谢你。

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
;