plsql列出包含空值的所有table.column

Question

我想查找其中包含null值的一組表的所有列。

我能找到的表和列名

SELECT TABLE_NAME, COLUMN_NAME 
FROM user_tab_cols 
where nullable='Y' 
     and table_name in ('myTalbe', 'myTable2'); 

而且還要檢查是否是空

select count(*) from myTable where myColumn is null; 

，但我怎能把這個toghether有作爲結果

table_name  column_name 
myTable  myColumn 
myTable  myCol2 
myTable2  col4 

Answer 1

一種方法可以用一些動態SQL，但這需要一些PL/SQL代碼;下面只使用SQL來得到你所需要的結果：

select * 
from (
     select table_name, 
       column_name, 
       to_number(extractvalue(xmltype(dbms_xmlgen.getxml('select count(*) c from '||table_name || ' where ' || column_name || ' is null')),'/ROWSET/ROW/C')) as rowcount 
     from user_tab_columns 
     where nullable='Y' 
      and table_name in ('myTalbe', 'myTable2') 
    ) 
where rowcount > 0 

這可能是使用動態SQL的方法：

declare 
    type tableOfNumber is table of number; 
    type tableOfChar is table of varchar2(30); 
    -- 
    vSQl   varchar2(4000); 
    vListNumbers tableOfNumber; 
    vListTables  tableOfChar; 
    vListColumns tableOfChar; 
begin 
    select listagg('select ''' || 
         table_name || ''' as table_name, ''' || 
         column_name || ''' as column_name, count(*) as rowCount from ' || 
         table_name || 
         ' where ' || 
         column_name || 
         ' is null having count(*) > 0' , 
        ' UNION ALL ' 
        ) within group (order by table_name, column_name) 
    into vSQL 
    from user_tab_columns 
    where nullable='Y' 
      and table_name in ('myTalbe', 'myTable2'); 
    -- 
    dbms_output.put_line(vSQL); 


    /* whatever you may want to do with the query */ 


    /* for example, fetch into some variables and print the result */ 
    execute immediate vSQL 
    bulk collect into vListTables, vListColumns, vListNumbers; 
    -- 
    if vListTables.count() > 0 then 
     for i in vListTables.first .. vListTables.last loop 
      dbms_output.put_line('Table ' || vListTables(i) || 
            ', column ' || vListColumns(i) || 
            ', number of nulls: ' || vListNumbers(i) 
           ); 
     end loop; 
    end if; 
end; 

Answer 2

這裏有一個程序，我寫了一段時間後，以這樣做。它將輸出所需的DDL以使那些不可空的列（但不包含任何空值）不可空。

https://connormcdonald.wordpress.com/2016/03/11/tightening-up-your-data-model/

它可以做一個模式或單個表的任務。