请教一个 SQL 的问题，来个大佬帮忙丁真下

SELECT
	p.project_code AS 项目编码,
	p.project_name AS 项目名称,
	count( e.id ) AS 建筑数量,
	count( d.id ) AS 设备数量 
FROM
	`emp_project` p
	LEFT JOIN `architecture` e ON p.id = e.`project_id` 
	AND e.`is_active` = 1 
	AND e.`level` = 30 
	AND e.`source_type` = 'Z'
	LEFT JOIN `project_device` d ON p.id = d.project_id 
	AND d.is_active = 1 
	AND d.device_type IN ( 1, 2, 3, 4 ) 
WHERE
	p.`is_active` = 1 
	AND p.`source_type` = 'Z' 
GROUP BY
	p.id

SELECT
	p.project_code AS 项目编码,
	p.project_name AS 项目名称,
	en.encount AS 建筑数量,
	de.decount AS 设备数量 
FROM
	`emp_project` p
	LEFT JOIN ( SELECT `project_id`, count(*) AS encount FROM `architecture` WHERE `level` = 30 AND `is_active` = 1 
	AND `source_type` = 'Z' GROUP BY `project_id` ) en ON p.id = en.`project_id`
	LEFT JOIN (
	SELECT
		`project_id`,
		count(*) AS decount 
	FROM
		`project_device` 
	WHERE
		`is_active` = 1 
		AND `device_type` IN ( 1, 2, 3, 4 ) 
	GROUP BY
		`project_id` 
	) de ON p.id = de.project_id 
WHERE
	p.`is_active` = 1 
	AND p.`source_type` = 'Z'

这两段 sql 在同一个库里执行，结果天差地别，但是从连接和分组以及查询条件来看，感觉不出来有什么差异，大佬们能不能一眼丁真帮看下原因

ZZ74

328 天前

注意 left join
第一句 p 中 project id 就算 e ，d 中没有对应的也会被 count
第二句就不会有问题

而且现在 sql 都那么宽泛了吗？第一句 sql 你 count 的话不应该是 group by project_code 和 name 为啥要是 id...
怎么说呢你这两个统计值应该做成两个 sql 用 inner join....

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