SQL ROLLUP或Union？

Question

我试图让条目的总计数，但不幸的是我不相信汇总会是最好的选择：

SELECT BUSINESS_STATUS_NAME, 
    PENDING_ITEMS, 
    DATAGROUP 
FROM PAYMENTS 
WHERE STATUS LIKE '%PROCESS%'; 

这将产生：

BUSINESS_STATUS_NAME  PENDING_ITEMS  DATAGROUP 
PROCESSING DATA   34    PRODUCT 
PROCESSING INS   40    SERVICE 

我想获得一个大总计低于，但ROLLUP给我的小计，因为它包括数据组列。我只需要悬而未决的项目总计，但我需要显示数据组。 UNION有总和（pending_items）选择查询会更好吗？

BUSINESS_STATUS_NAME  PENDING_ITEMS  DATAGROUP 
PROCESSING DATA   34    PRODUCT 
PROCESSING INS   40    SERVICE 
GRAND TOTAL **   74 

谢谢！

Answer 1

您可以使用rollup，但你需要一个聚集查询：

SELECT BUSINESS_STATUS_NAME, 
     SUM(PENDING_ITEMS) as PENDING_ITEMS, 
     DATAGROUP 
FROM PAYMENTS 
WHERE STATUS LIKE '%PROCESS%' 
GROUP BY ROLLUP (BUSINESS_STATUS_NAME, DATAGROUP); 

我怀疑有这样的一个union all之间的性能差异。但是，请注意，这可保证将汇总行作为结果集中的最后一行。

Answer 2

我会使用ROLLUP，为了清晰和性能。

说你有一个这样的示例表：

create table payments (business_status_name, pending_items, datagroup) as (
    select 'PROCESSING DATA', 10, 'PRODUCT' from dual union all 
    select 'PROCESSING DATA', 5, 'PRODUCT' from dual union all 
    select 'PROCESSING DATA', 2, 'SERVICE' from dual union all 
    select 'PROCESSING INS', 10, 'SERVICE' from dual union all 
    select 'PROCESSING INS', 10, 'SERVICE' from dual union all 
    select 'PROCESSING INS', 10, 'PRODUCT' from dual 
) 

这是ROLLUP的方式（注意括号来改变分组的逻辑）：

SELECT BUSINESS_STATUS_NAME, 
     SUM(PENDING_ITEMS) as PENDING_ITEMS, 
     DATAGROUP 
FROM PAYMENTS 
GROUP BY ROLLUP ((BUSINESS_STATUS_NAME, DATAGROUP)) 

结果：

BUSINESS_STATUS PENDING_ITEMS DATAGRO 
--------------- ------------- ------- 
PROCESSING INS    10 PRODUCT 
PROCESSING INS    20 SERVICE 
PROCESSING DATA   15 PRODUCT 
PROCESSING DATA    2 SERVICE 
          47 

该计划：

--------------------------------------------------------------------------------- 
| Id | Operation   | Name  | Rows | Bytes | Cost (%CPU)| Time  | 
--------------------------------------------------------------------------------- 
| 0 | SELECT STATEMENT  |   |  6 | 186 |  4 (25)| 00:00:01 | 
| 1 | SORT GROUP BY ROLLUP|   |  6 | 186 |  4 (25)| 00:00:01 | 
| 2 | TABLE ACCESS FULL | PAYMENTS |  6 | 186 |  3 (0)| 00:00:01 | 
--------------------------------------------------------------------------------- 

这是UNION ALL：

SELECT BUSINESS_STATUS_NAME, 
     SUM(PENDING_ITEMS) as PENDING_ITEMS, 
     DATAGROUP 
FROM PAYMENTS 
GROUP BY BUSINESS_STATUS_NAME, DATAGROUP 
UNION ALL 
SELECT NULL, SUM(PENDING_ITEMS), NULL 
FROM PAYMENTS; 

结果比ROLLUP相同：

BUSINESS_STATUS PENDING_ITEMS DATAGRO 
--------------- ------------- ------- 
PROCESSING INS    20 SERVICE 
PROCESSING INS    10 PRODUCT 
PROCESSING DATA   15 PRODUCT 
PROCESSING DATA    2 SERVICE 
          47 

的计划也不是那么好，TWO FULL SCANS：

-------------------------------------------------------------------------------- 
| Id | Operation   | Name  | Rows | Bytes | Cost (%CPU)| Time  | 
-------------------------------------------------------------------------------- 
| 0 | SELECT STATEMENT |   |  7 | 199 |  7 (58)| 00:00:01 | 
| 1 | UNION-ALL   |   |  |  |   |   | 
| 2 | HASH GROUP BY  |   |  6 | 186 |  4 (25)| 00:00:01 | 
| 3 | TABLE ACCESS FULL| PAYMENTS |  6 | 186 |  3 (0)| 00:00:01 | 
| 4 | SORT AGGREGATE |   |  1 | 13 |   |   | 
| 5 | TABLE ACCESS FULL| PAYMENTS |  6 | 78 |  3 (0)| 00:00:01 | 
-------------------------------------------------------------------------------- 

这当然只有一个有少量记录的小示例，没有索引，......因此，真实表格上的内容可能会有所不同，但我仍然认为ROLLUP应该比UNION ALL更好。

在一个简单的情况下，完全等于你的，这将是这两种方法的计划：

SELECT BUSINESS_STATUS_NAME, 
     SUM(PENDING_ITEMS) as PENDING_ITEMS, 
     DATAGROUP 
FROM PAYMENTS 
GROUP BY ROLLUP ((BUSINESS_STATUS_NAME, DATAGROUP)) 

--------------------------------------------------------------------------------- 
| Id | Operation   | Name  | Rows | Bytes | Cost (%CPU)| Time  | 
--------------------------------------------------------------------------------- 
| 0 | SELECT STATEMENT  |   |  2 | 62 |  4 (25)| 00:00:01 | 
| 1 | SORT GROUP BY ROLLUP|   |  2 | 62 |  4 (25)| 00:00:01 | 
| 2 | TABLE ACCESS FULL | PAYMENTS |  2 | 62 |  3 (0)| 00:00:01 | 
--------------------------------------------------------------------------------- 

SELECT BUSINESS_STATUS_NAME, 
     PENDING_ITEMS, 
     DATAGROUP 
FROM PAYMENTS 
UNION ALL 
SELECT NULL, 
     SUM(PENDING_ITEMS), 
     NULL 
FROM PAYMENTS  

-------------------------------------------------------------------------------- 
| Id | Operation   | Name  | Rows | Bytes | Cost (%CPU)| Time  | 
-------------------------------------------------------------------------------- 
| 0 | SELECT STATEMENT |   |  3 | 75 |  6 (50)| 00:00:01 | 
| 1 | UNION-ALL   |   |  |  |   |   | 
| 2 | TABLE ACCESS FULL | PAYMENTS |  2 | 62 |  3 (0)| 00:00:01 | 
| 3 | SORT AGGREGATE |   |  1 | 13 |   |   | 
| 4 | TABLE ACCESS FULL| PAYMENTS |  2 | 26 |  3 (0)| 00:00:01 | 
-------------------------------------------------------------------------------- 

ROLLUP仍然有一个表扫描一个更好的计划。