使 SQL 查询动态化

Question

我有以下 SQL 查询，我想知道我是否可以使它的 SUM() 部分动态化，这样我就不必输入 category_id（2 和 3）

SELECT 
a.project_id,
COUNT(a.id) AS Total,
SUM(CASE WHEN a.category_id = 2 AND a.`status` < 80 THEN 1 ELSE 0 END) AS 'Bugs En cours',
SUM(CASE WHEN a.category_id = 2 AND a.`status` >= 80 THEN 1 ELSE 0 END) AS 'Bugs Resolu',
SUM(CASE WHEN a.category_id = 3 AND a.`status` < 80 THEN 1 ELSE 0 END) AS 'Ameliorations En cours',
SUM(CASE WHEN a.category_id = 3 AND a.`status` >= 80 THEN 1 ELSE 0 END) AS 'Ameliorations Resolu'
FROM bugs a 
GROUP BY a.project_id
HAVING COUNT(a.id) > 0

目标是根据 category_id 和 status（'En cours' 或 'Resolu')

此查询中的问题是，如果我们添加另一个类别，我将不得不手动编辑此查询，这并不理想。

Answer 1

下面的动态 sql 正在根据具有类别的参考 table 构建条件总和。

SET @sums := (
SELECT GROUP_CONCAT(
CONCAT(
', SUM(CASE WHEN category_id = ', category_id, 
' AND `status` <  80 THEN 1 ELSE 0 END)', 
' AS `', category_name, ' En cours`', CHAR(10),
', SUM(CASE WHEN category_id = ', category_id, 
' AND `status` >= 80 THEN 1 ELSE 0 END)',
' AS `', category_name, ' Resolu`', CHAR(10)
) ORDER BY category_id SEPARATOR '') as sums
FROM categories
);

SET @dynsql := CONCAT('SELECT', CHAR(10), '  bug.project_id', CHAR(10),
', COUNT(bug.id) AS Total', CHAR(10),
@sums, 
'FROM bugs bug', CHAR(10),
'GROUP BY bug.project_id', CHAR(10),
'HAVING COUNT(bug.id) > 0;');

-- SELECT @dynsql AS dynsql;
PREPARE dyn_stmt FROM @dynsql;
EXECUTE dyn_stmt;
DEALLOCATE PREPARE dyn_stmt;

project_id	Total	Conneries En cours	Conneries Resolu	Bugs En cours	Bugs Resolu	Ameliorations En cours	Ameliorations Resolu
0	5	1	0	1	1	1	1

演示 db<>fiddle here

使 SQL 查询动态化

Making SQL query dynamic

mysql

sql

pivot

group-by

dynamic-sql