有关Quick BI中Case子句中多次使用lod函数返回空值问题分析
一、Quick BI中的lod_ include函数
lod_ include {维度1[,维度2]...:聚合表达式[:过滤条件]}
作用：将表达式中的维度一起作为分组依据进行订算。其中，
1) 维度1[,维度2]... ：声明维度，指定聚合表达式要连接到的一个或多个维度。使用逗号分隔各个维度。
2) 聚合表达式：聚合表达式是所执行的计算，用于定义目标维度。
3) 过滤条件：可以通过对前面的声明维度设定条件进行过滤，非必须。
二、、问题描述
| 3月 |
4月 |
5月 |
合计 |
|
| 总结存数量 |
35116176 |
36286140 |
37120427 |
108522743 |
在Quick BI数据集新建计算字段” 总结存数量=CASE WHEN MAX([月份])='3月' THEN lod_include{[月份]:SUM([结存数量]):[月份]='3月'} WHEN MAX([月份])='4月' THEN lod_include{[月份]:SUM([结存数量]):[月份]='4月'} WHEN MAX([月份])='5月' THEN lod_include{[月份]:SUM([结存数量]):[月份]='5月'} 。
END”
在Quick BI仪表板新建交叉表，以‘月份’为行，以‘总结存数量’为列，执行结果“数据返回为空“，这个结果显示不正确。
三、问题分析
查看SQL代码
SELECT
LOD_TM.`LOD_2C07D23FC7BBAA` AS LOD_0,
CASE
WHEN LOD_TM.`temp_calculation_0` = '3月' THEN LOD_TP_0.`LOD_C5682C34D69BEC`
WHEN LOD_TM.`temp_calculation_0` = '4月' THEN LOD_TP_1.`LOD_D78F97D23AEDC1`
WHEN LOD_TM.`temp_calculation_0` = '5月' THEN LOD_TP_2.`LOD_5B3771E3CF7947`
END AS LOD_1
FROM
(
SELECT
ATN_T_1_.`月份` AS LOD_2C07D23FC7BBAA,
MAX(ATN_T_1_.`月份`) AS temp_calculation_0
FROM
`terminaldata2`.`account` AS ATN_T_1_
GROUP BY
ATN_T_1_.`月份`
ORDER BY
LOD_2C07D23FC7BBAA ASC
LIMIT
0, 20
) AS LOD_TM
INNER JOIN (
SELECT
LOD_TL.`LOD_2C07D23FC7BBAA` AS LOD_2C07D23FC7BBAA,
LOD_TR.`LOD_measure_result` AS LOD_C5682C34D69BEC
FROM
(
SELECT
ATN_T_1_.`月份` AS LOD_2C07D23FC7BBAA
FROM
`terminaldata2`.`account` AS ATN_T_1_
GROUP BY
ATN_T_1_.`月份`
) AS LOD_TL
INNER JOIN (
SELECT
SUM(
ATN_T_1_.`结存数量`
) AS LOD_measure_result,
ATN_T_1_.`月份` AS LOD_2C07D23FC7BBAA
FROM
`terminaldata2`.`account` AS ATN_T_1_
WHERE
ATN_T_1_.`月份` = '3月'
GROUP BY
ATN_T_1_.`月份`
) AS LOD_TR ON LOD_TL.`LOD_2C07D23FC7BBAA` = LOD_TR.`LOD_2C07D23FC7BBAA`
GROUP BY
LOD_TL.`LOD_2C07D23FC7BBAA`
) AS LOD_TP_0 ON LOD_TM.`LOD_2C07D23FC7BBAA` = LOD_TP_0.`LOD_2C07D23FC7BBAA`
INNER JOIN (
SELECT
LOD_TL.`LOD_2C07D23FC7BBAA` AS LOD_2C07D23FC7BBAA,
LOD_TR.`LOD_measure_result` AS LOD_D78F97D23AEDC1
FROM
(
SELECT
ATN_T_1_.`月份` AS LOD_2C07D23FC7BBAA
FROM
`terminaldata2`.`account` AS ATN_T_1_
GROUP BY
ATN_T_1_.`月份`
) AS LOD_TL
INNER JOIN (
SELECT
SUM(
ATN_T_1_.`结存数量`
) AS LOD_measure_result,
ATN_T_1_.`月份` AS LOD_2C07D23FC7BBAA
FROM
`terminaldata2`.`account` AS ATN_T_1_
WHERE
ATN_T_1_.`月份` = '4月'
GROUP BY
ATN_T_1_.`月份`
) AS LOD_TR ON LOD_TL.`LOD_2C07D23FC7BBAA` = LOD_TR.`LOD_2C07D23FC7BBAA`
GROUP BY
LOD_TL.`LOD_2C07D23FC7BBAA`
) AS LOD_TP_1 ON LOD_TM.`LOD_2C07D23FC7BBAA` = LOD_TP_1.`LOD_2C07D23FC7BBAA`
INNER JOIN (
SELECT
LOD_TL.`LOD_2C07D23FC7BBAA` AS LOD_2C07D23FC7BBAA,
LOD_TR.`LOD_measure_result` AS LOD_5B3771E3CF7947
FROM
(
SELECT
ATN_T_1_.`月份` AS LOD_2C07D23FC7BBAA
FROM
`terminaldata2`.`account` AS ATN_T_1_
GROUP BY
ATN_T_1_.`月份`
) AS LOD_TL
INNER JOIN (
SELECT
SUM(
ATN_T_1_.`结存数量`
) AS LOD_measure_result,
ATN_T_1_.`月份` AS LOD_2C07D23FC7BBAA
FROM
`terminaldata2`.`account` AS ATN_T_1_
WHERE
ATN_T_1_.`月份` = '5月'
GROUP BY
ATN_T_1_.`月份`
) AS LOD_TR ON LOD_TL.`LOD_2C07D23FC7BBAA` = LOD_TR.`LOD_2C07D23FC7BBAA`
GROUP BY
LOD_TL.`LOD_2C07D23FC7BBAA`
) AS LOD_TP_2 ON LOD_TM.`LOD_2C07D23FC7BBAA` = LOD_TP_2.`LOD_2C07D23FC7BBAA`
SELECT
COUNT(1) AS query_count
FROM
(
SELECT
LOD_TM.`LOD_2C07D23FC7BBAA` AS LOD_0,
CASE
WHEN LOD_TM.`temp_calculation_0` = '3月' THEN LOD_TP_0.`LOD_C5682C34D69BEC`
WHEN LOD_TM.`temp_calculation_0` = '4月' THEN LOD_TP_1.`LOD_D78F97D23AEDC1`
WHEN LOD_TM.`temp_calculation_0` = '5月' THEN LOD_TP_2.`LOD_5B3771E3CF7947`
END AS LOD_1
FROM
(
SELECT
ATN_T_1_.`月份` AS LOD_2C07D23FC7BBAA,
MAX(ATN_T_1_.`月份`) AS temp_calculation_0
FROM
`terminaldata2`.`account` AS ATN_T_1_
GROUP BY
ATN_T_1_.`月份`
) AS LOD_TM
INNER JOIN (
SELECT
LOD_TL.`LOD_2C07D23FC7BBAA` AS LOD_2C07D23FC7BBAA,
LOD_TR.`LOD_measure_result` AS LOD_C5682C34D69BEC
FROM
(
SELECT
ATN_T_1_.`月份` AS LOD_2C07D23FC7BBAA
FROM
`terminaldata2`.`account` AS ATN_T_1_
GROUP BY
ATN_T_1_.`月份`
) AS LOD_TL
INNER JOIN (
SELECT
SUM(
ATN_T_1_.`结存数量`
) AS LOD_measure_result,
ATN_T_1_.`月份` AS LOD_2C07D23FC7BBAA
FROM
`terminaldata2`.`account` AS ATN_T_1_
WHERE
ATN_T_1_.`月份` = '3月'
GROUP BY
ATN_T_1_.`月份`
) AS LOD_TR ON LOD_TL.`LOD_2C07D23FC7BBAA` = LOD_TR.`LOD_2C07D23FC7BBAA`
GROUP BY
LOD_TL.`LOD_2C07D23FC7BBAA`
) AS LOD_TP_0 ON LOD_TM.`LOD_2C07D23FC7BBAA` = LOD_TP_0.`LOD_2C07D23FC7BBAA`
INNER JOIN (
SELECT
LOD_TL.`LOD_2C07D23FC7BBAA` AS LOD_2C07D23FC7BBAA,
LOD_TR.`LOD_measure_result` AS LOD_D78F97D23AEDC1
FROM
(
SELECT
ATN_T_1_.`月份` AS LOD_2C07D23FC7BBAA
FROM
`terminaldata2`.`account` AS ATN_T_1_
GROUP BY
ATN_T_1_.`月份`
) AS LOD_TL
INNER JOIN (
SELECT
SUM(
ATN_T_1_.`结存数量`
) AS LOD_measure_result,
ATN_T_1_.`月份` AS LOD_2C07D23FC7BBAA
FROM
`terminaldata2`.`account` AS ATN_T_1_
WHERE
ATN_T_1_.`月份` = '4月'
GROUP BY
ATN_T_1_.`月份`
) AS LOD_TR ON LOD_TL.`LOD_2C07D23FC7BBAA` = LOD_TR.`LOD_2C07D23FC7BBAA`
GROUP BY
LOD_TL.`LOD_2C07D23FC7BBAA`
) AS LOD_TP_1 ON LOD_TM.`LOD_2C07D23FC7BBAA` = LOD_TP_1.`LOD_2C07D23FC7BBAA`
INNER JOIN (
SELECT
LOD_TL.`LOD_2C07D23FC7BBAA` AS LOD_2C07D23FC7BBAA,
LOD_TR.`LOD_measure_result` AS LOD_5B3771E3CF7947
FROM
(
SELECT
ATN_T_1_.`月份` AS LOD_2C07D23FC7BBAA
FROM
`terminaldata2`.`account` AS ATN_T_1_
GROUP BY
ATN_T_1_.`月份`
) AS LOD_TL
INNER JOIN (
SELECT
SUM(
ATN_T_1_.`结存数量`
) AS LOD_measure_result,
ATN_T_1_.`月份` AS LOD_2C07D23FC7BBAA
FROM
`terminaldata2`.`account` AS ATN_T_1_
WHERE
ATN_T_1_.`月份` = '5月'
GROUP BY
ATN_T_1_.`月份`
) AS LOD_TR ON LOD_TL.`LOD_2C07D23FC7BBAA` = LOD_TR.`LOD_2C07D23FC7BBAA`
GROUP BY
LOD_TL.`LOD_2C07D23FC7BBAA`
) AS LOD_TP_2 ON LOD_TM.`LOD_2C07D23FC7BBAA` = LOD_TP_2.`LOD_2C07D23FC7BBAA`
) AS a以WHEN MAX([月份])='3月' THEN lod_include{[月份]:SUM([结存数量]):[月份]='3月'}为例分析：
上述代码，中LOD_TM表结果为
| LOD_2C07D23FC7BBAA |
temp_calculation_0 |
| 3月 |
3月 |
| 4月 |
4月 |
| 5月 |
5月 |
LOD_TL表结果为
| LOD_2C07D23FC7BBAA |
| 3月 |
| 4月 |
| 5月 |
LOD_TR表结果为
| LOD_measure_result |
LOD_2C07D23FC7BBAA |
| 35116176 |
3月 |
LOD_TL与LOD_TR通过条件”ON LOD_TL.`LOD_2C07D23FC7BBAA` = LOD_TR.`LOD_2C07D23FC7BBAA` GROUP BY LOD_TL.`LOD_2C07D23FC7BBAA`”进行内连接（INNER JOIN）得到表LOD_TP_0，LOD_TP_0结果为：
| LOD_2C07D23FC7BBAA |
LOD_C5682C34D69BEC |
| 3月 |
35116176 |
LOD_TM与LOD_TP_0通过条件“ON LOD_TM.`LOD_2C07D23FC7BBAA` = LOD_TP_0.`LOD_2C07D23FC7BBAA` “进行内连接（INNER JOIN），得到的结果为（这里称为表A1，由于是内连接，所以4月、5月无法显示）：
| LOD_2C07D23FC7BBAA |
temp_calculation_0 |
LOD_C5682C34D69BEC（LOD_TP_0） |
| 3月 |
3月 |
35116176 |
同理，当“WHEN MAX([月份])='4月' THEN lod_include{[月份]:SUM([结存数量]):[月份]='4月'}“，得到的结果为（这里称为表A2，由于是内连接，所以3月、5月无法显示）：
| LOD_2C07D23FC7BBAA |
temp_calculation_0 |
LOD_C5682C34D69BEC（LOD_TP_1） |
| 4月 |
4月 |
36286140 |
同理，当“WHEN MAX([月份])='5月' THEN lod_include{[月份]:SUM([结存数量]):[月份]='5月'}“，得到的结果为（这里称为表A3，由于是内连接，所以3月、4月无法显示）：
| LOD_2C07D23FC7BBAA |
temp_calculation_0 |
LOD_C5682C34D69BEC（LOD_TP_2） |
| 5月 |
5月 |
37120427 |
表A1、表A2、表A3默认进行通过字段‘LOD_2C07D23FC7BBAA‘进行内连接（INNER JOIN），由于表A1中只有’3月‘，表A2中只有’4月‘，表A3中只有’5月‘，内连接的表必然为空表。
四、优化建议
既然表A1、表A2、表A3之间默认是内连接（INNER JOIN），只需要让表A1、表A2、表A3中同时存在“3月“、”4月“、”5月“即可以。也就是把LOD_TM与LOD_TP_0通过条件“ON LOD_TM.`LOD_2C07D23FC7BBAA` = LOD_TP_0.`LOD_2C07D23FC7BBAA` “进行的内连接（INNER JOIN），改为左外连接（LEFT JOIN）。LOD_TP_1、LOD_TP_2同理进行相同操作。具体做法即将上述第43、101、159、261、319、377行代码由INNER JOIN 改为 LEFT JOIN。这样得到的表A1：
| LOD_2C07D23FC7BBAA |
temp_calculation_0 |
LOD_C5682C34D69BEC（LOD_TP_0） |
| 3月 |
3月 |
35116176 |
| 4月 |
4月 |
NULL |
| 5月 |
5月 |
NULL |
表A2：
| LOD_2C07D23FC7BBAA |
temp_calculation_0 |
LOD_C5682C34D69BEC（LOD_TP_0） |
| 3月 |
3月 |
NULL |
| 4月 |
4月 |
36286140 |
| 5月 |
5月 |
NULL |
表A3：
| LOD_2C07D23FC7BBAA |
temp_calculation_0 |
LOD_C5682C34D69BEC（LOD_TP_0） |
| 3月 |
3月 |
NULL |
| 4月 |
4月 |
NULL |
| 5月 |
5月 |
37120427 |
新得到的表A1、表A2、表A3再进行内连接（INNER JOIN）得到的结果是：
| LOD_2C07D23FC7BBAA |
temp_calculation_0 |
LOD_C5682C34D69BEC（LOD_TP_0） |
| 3月 |
3月 |
35116176 |
| 4月 |
4月 |
36286140 |
| 5月 |
5月 |
37120427 |