[英]COUNT in GROUP_CONCAT not working while querying a dynamic column table
我有一個名為table1
的表,如下所示:
id period value name
1 2020-06-01 3 anna
2 2020-06-01 2 anna
3 2020-06-01 3 anna
4 2020-06-01 1 juned
5 2020-06-01 3 juned
6 2020-06-01 2 juned
7 2020-07-01 3 anna
8 2020-07-01 2 anna
9 2020-07-01 2 anna
10 2020-07-01 3 juned
11 2020-07-01 3 juned
12 2020-07-01 3 juned
我希望查詢的結果顯示值3
的計數
name 2020-06-01 2020-07-01
anna 2 2
juned 1 3
我試過這是代碼,但它導致錯誤#1111 - invalid use of group function
SET @sql = NULL;
SELECT
GROUP_CONCAT(DISTINCT
CONCAT(
'MAX(IF (table1.period = "',
table1.period, '", COUNT(CASE WHEN value = 3 THEN 1 END), 0)) AS `',
table1.period, '`'
)
) INTO @sql
FROM table1;
SET @sql = CONCAT(
'SELECT name, ',
@sql,
' FROM table1 GROUP BY name'
);
PREPARE stmt FROM @sql;
EXECUTE stmt;
我會將動態 SQL 編寫為:
SET @sql = NULL;
SELECT GROUP_CONCAT(DISTINCT 'SUM(value = 3 AND period = ''', period, ''') AS `', period, '`')
INTO @sql
FROM table1;
SET @sql = CONCAT('SELECT name, ', @sql, ' FROM table1 GROUP BY name');
-- debug
select @sql;
PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
您的代碼的主要問題是您在聚合函數中表述條件表達式的方式。 還:
在GROUP_CONCAT()
不需要CONCAT()
:您可以在GROUP_CONCAT()
放置多個值,用字符串分隔
對文字字符串使用單引號而不是雙引號
執行查詢后, DEALLOCATE
語句處理程序
DB Fiddle 上的演示- 首先感謝會見 Soni 以創建小提琴。
生成的sql:
| @sql | | :------------------------------------------------------------------------------------------------------------------------------------------------------- | | SELECT name, SUM(value = 3 AND period = '2020-06-01') AS `2020-06-01`,SUM(value = 3 AND period = '2020-07-01') AS `2020-07-01` FROM table1 GROUP BY name |
查詢結果:
name | 2020-06-01 | 2020-07-01 :---- | ---------: | ---------: anna | 2 | 1 juned | 1 | 3
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.