Question

我有一张桌子：

表1

col1        col2        col3        col4
a           b           (null)      c
a           b           (null)      c
a           (null)      (null)      c
(null)      b           (null)      (null)
a           b           (null)      (null)
a           b           (null)      (null)

我表中大约有300列。我需要查找每个非空列的值计数，而无需在表中键入每个列名称。

输出为：

column_name         count_of_non_null
col1                5
col2                5
col3                0
col4                3

有办法吗？

Answer 1

您需要动态PL / SQL来编写条件聚合类型的查询：

select 'col1' col, count(case when col1 is null then 1 end) from table1
union all
select 'col2' col, count(case when col2 is null then 1 end) from table1

因此，您的PL / SQL代码将遵循以下原则

declare 
  v_cmd varchar2(10000);
begin 
  for c_column in (select column_name from user_tab_columns where table_name = 'table1') loop
    v_counter := v_counter + 1;
    v_cmd := v_cmd || 'select ''' || c_column.column_name  || ''' col, count(case when ' || c_column.column_name || ' is null then 1 end) from table1 union all ';
  end loop;
  execute immediate left(v_cmd, length(v_cmd) - 11);
end;
/

我没有测试

Answer 2

希望您可以使用以下查询来实现。

select col,cnt from (
select col1 col, sum(case when col1 is not null then 1 else 0 end) cnt from tableA group by col1
union all 
select col2 col, sum(case when col2 is not null then 1 else 0 end) cnt from tableA group by col2
union all
select col3 col, sum(case when col3 is not null then 1 else 0 end) cnt from tableA group by col3
union all
select col4 col, sum(case when col4 is not null then 1 else 0 end) cnt from tableA group by col4
)

表中具有非空值的每个列的计数-Oracle

2 个答案: