爲動態原生SQL查詢的結果執行結果行

Question

我正在考慮這一點。我對動態SQL相當陌生，所以我可能不會問Google正確的問題，但這是我正在嘗試做的事情......我使用動態SQL進行查詢。當我運行該查詢時，它會產生多行。所有這些行（大約30）組成一個單一的聯合查詢。我可以複製所有這些行並粘貼到一個新的查詢並運行 - 工作正常，但我需要做的是在單個查詢中運行這一切。我查了一下使用execute immediate和fetch的例子，但我似乎無法讓他們真正吐出數據......他們最終只是說「執行成功」，但實際上並沒有產生任何結果行。下面的SQL的結果列名是「qry_txt」 - 而不是以面值生成它，我想將它作爲查詢來執行。再一次，我可能沒有說清楚，但我基本上試圖將2個查詢（涉及手動複製/粘貼步驟）轉換爲單個查詢。希望這是有道理...

這裏是我的SQL：

Select CASE when 
lead(ROWNUM) over(order by ROWNUM) is null then 
'SELECT '||''''||T.TABLE_NAME||''''||' as TABLE_NAME,'||''''||T.COLUMN_NAME||''''||' as COLUMN_NAME, cast('|| T.COLUMN_NAME ||' as 
varchar2(100)) as SAMPLE_DATA || 
from rpt.'||T.TABLE_NAME ||' where '||T.COLUMN_NAME||' is not null and ROWNUM=1;' 
else 
'SELECT '||''''||T.TABLE_NAME||''''||' as TABLE_NAME,'||''''||T.COLUMN_NAME||''''||' as COLUMN_NAME, cast('|| T.COLUMN_NAME ||' as 
varchar2(100)) as SAMPLE_DATA from rpt.'||T.TABLE_NAME ||' where '||T.COLUMN_NAME||' is not null and ROWNUM=1 union ' end as qry_txt 
from all_tab_columns t where T.OWNER='rpt' and T.DATA_TYPE != 'BLOB' and T.DATA_TYPE != 'LONG' and T.TABLE_NAME = 'NME_DMN' 
ORDER BY ROWNUM asc; 

Answer 1

你不能寫在SQL動態查詢。你需要使用PLSQL塊來實現這一點。請看你如何做到這一點。 PS：代碼未經測試。

declare 
    var1 <decalration same of column in select list> ; 
    var2 <decalration same of column in select list> ; 
    var3 <decalration same of column in select list> ; 
    .... 
    varn ; 

begin 
    for i in (SELECT LEAD (ROWNUM) OVER (ORDER BY ROWNUM) COl1 
       FROM all_tab_columns t 
       WHERE  T.OWNER = 'rpt' 
        AND T.DATA_TYPE != 'BLOB' 
        AND T.DATA_TYPE != 'LONG' 
        AND T.TABLE_NAME = 'NME_DMN' 
      ORDER BY ROWNUM ASC) 

    Loop 

    If i.col1 IS NULL Then 

    execute immediate 'SELECT ' 
          || '''' 
          || T.TABLE_NAME 
          || '''' 
          || ' as TABLE_NAME,' 
          || '''' 
          || T.COLUMN_NAME 
          || '''' 
          || ' as COLUMN_NAME, cast(' 
          || T.COLUMN_NAME 
          || ' as 
           varchar2(100)) as SAMPLE_DATA || 
          from rpt.' 
          || T.TABLE_NAME 
          || ' where ' 
          || T.COLUMN_NAME 
          || ' is not null and ROWNUM=1' into var1 , var2 ,var3 ....varn; 

    Else 

     execute immediate 'SELECT ' 
          || '''' 
          || T.TABLE_NAME 
          || '''' 
          || ' as TABLE_NAME,' 
          || '''' 
          || T.COLUMN_NAME 
          || '''' 
          || ' as COLUMN_NAME, cast(' 
          || T.COLUMN_NAME 
          || ' as 
      varchar2(100)) as SAMPLE_DATA from rpt.' 
          || T.TABLE_NAME 
          || ' where ' 
          || T.COLUMN_NAME 
          || ' is not null and ROWNUM=1' into var1 , var2 ,var3 ....varn; 

    end if; 

    End Loop;    

    exception 
    when others then 
    dbms_output.put_lin(sqlcode ||'--'||sqlerrm); 

End;