Mysql中几种sql的常见用法

如何使用非默认的排序。例如使用213之类的排序

可以使用如下方法

SELECT DISTINCT
	pg.part_grp_id,
	pg.part_grp_name,
	pg.equip_category_id
FROM
	cost_part_grp pg,
	cost_part_kit pk,
	cost_part_event pe
WHERE
	pe.mdl_ver_id IN (
		SELECT
			s.mdl_ver_id
		FROM
			cost_fleet_model s
		WHERE
			s.fleet_id = 1002
	)
AND pe.part_kit_id = pk.part_kit_id
AND pk.part_grp_id = pg.part_grp_id
ORDER BY
	CASE pg.equip_category_id
WHEN 2 THEN
	1
WHEN 1 THEN
	2
WHEN 4 THEN
	3
ELSE
	4
END

原文链接：https://blog.csdn.net/skytalemcc/article/details/5883728

mysql如何更新替换某一个字段中的特定字符串

UPDATE t_bss_employees
SET mobilephone = REPLACE (mobilephone, "2129", "0000")
WHERE
	id IN (
		SELECT
			a.id
		FROM
			(
				SELECT
					id
				FROM
					t_bss_employees
				WHERE
					mobilephone IN (
						'18121299262',
						'18121299247',
						'18121299206',
						'18121299209'
					)
			) AS a
	)

将mobilephone字段中的2129字符串替换为0000

使用当前表为条件更新当前表。需要在条件处再添加一个（）构建一个虚拟表

求比例的sql

	select a.style, ROUND(
            b.num / a.sum * 100,
            2
        ) as styleRate from (SELECT
	count(qspc.id) sum
	,qq.style  style
	from  t_qc_security_plan_comment  qspc
		inner join t_qc_question qq
		on qq.id = qspc.question_id
		LEFT JOIN t_qc_address qa ON qa.id = qspc.address_id
		LEFT JOIN t_system_organ  so on qa.hospital =  so.id
		WHERE qq.scr_level is not NULL
		and qq.type = 3  and so.tenant_code = 'zzyy'
		GROUP BY style) a left join (SELECT
	count(qspc.id) num
	,qq.style  style
	from  t_qc_security_plan_comment  qspc
		inner join t_qc_question qq
		on qq.id = qspc.question_id
		LEFT JOIN t_qc_address qa ON qa.id = qspc.address_id
		LEFT JOIN t_system_organ  so on qa.hospital =  so.id
		WHERE qq.scr_level is not NULL
		and qq.type = 3  and so.tenant_code = 'zzyy'
		and qspc.is_bad =0
		GROUP BY style) b on a.style = b.style

计算逻辑是分别求总数和平均数。然后两数相除再用round求精度

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