製作的rownum null值

Question

我的SQL代碼，我想從COLUMN1每一個獨特的價值相同的ROWNUM。 例如在本例中，我想對ROWNUM 2,3和第2列的rownum 2

select rownum, 
    t1.column1 as column1, 
    t1.Column2 as column2, 
    t3.Column3 as column3 
from Table1 t1,Table3 t3,Table2 t2 
where t3.S_ID=t2.AS_ID 
and t2.KT_ID=t1.T_ID 

空值我如何實現這一點？

Answer 1

 This might help you... 

     select rownum,column1,column2,column3 from (

Select rownum,column1,column2,column3, 
row_number() over(partition by column1,column2 order by column1,column2) as analytic_rnm 
from(
select rownum, 
    column1 as column1, 
    Column2 as column2, 
    Column3 as column3 
from Table1 t1,Table3 t3,Table2 t2 
where t3.S_ID=t2.AS_ID 
and t2.KT_ID=t1.T_ID 
)X 
)M 
where analytic_rnm=1 

union all 
select NULL as rownum, 
column1,column2,column3 from (
Select rownum,column1,column2,column3, 
row_number() over(partition by column1,column2 order by column1,column2) as analytic_rnm 
from(
select rownum, 
    column1 as column1, 
    Column2 as column2, 
    Column3 as column3 
from Table1 t1,Table3 t3,Table2 t2 
where t3.S_ID=t2.AS_ID 
and t2.KT_ID=t1.T_ID 
)X)Y 
where analytic_rnm>1 

Answer 2

select 
    case when row_number() -- if it's the first row per group... 
      over(partition by column1 
        order by column3) = 1 
     then dense_rank() -- ... return 1,2,3 
      over(order by column1) 
     else null 
    end, 
    t1.column1 as column1, 
    t1.Column2 as column2, 
    t3.Column3 as column3 
from Table1 t1,Table3 t3,Table2 t2 
where t3.S_ID=t2.AS_ID 
and t2.KT_ID=t1.T_ID 

Answer 3

首先，學習正確的明確join語法。其次，你可以很容易地做你想要使用的是什麼lag()等分析功能：

select (case when column1 = lag(column1) over (order by column1, column3) 
      then NULL 
      else dense_rank() over (order by column1) 
     end) as rn, 
     t1.column1 as column1, 
     t1.Column2 as column2, 
     t3.Column3 as column3 
from Table1 t1 join 
    Table2 t2 
    on t2.KT_ID = t1.T_ID join 
    Table3 t3 
    on t3.S_ID = t2.AS_ID 
order by column1, column3; 

一些注意事項：

• SQL查詢返回無序結果集。如果您希望按特定順序排列行 - 或者在下次運行查詢時以相同順序排序 - 則請包含order by。
• 我任意添加column3來排序。它可以是任何列，使穩定。也就是說，每行都有一組唯一的訂單鍵，因此每次都有相同的順序。
• 相同的排序條件被用於lag()功能，但只能column1用於dense_rank()。
• 瞭解顯式join語法。它更強大，幾乎每個人都認爲它更易於閱讀。