MySQL优化：select brandName,have_vin_count,(select count(1) from epc_carmodel_skucount where ifnull(vin,'') <> '') as have_vin_sum_count, concat(round(have_vin_count/(select count(1) from epc_carmodel_skucount where ifnull(vin,'') <> '')*100, 2),'%') as have_vin_percent from (select b.brandName,count(distinct a.vehicleUUID) as have_vin_count from (select distinct vehicleUUID from epc_carmodel_skucount where ifnull(vin,'') <> '') a inner join ( select b.brandName,b.vehicleUUID from epc_material_sence_model a join ( select * from epc_bom_sence where brandName not in ('演示','测试','客服内测') and ifnull(brandName,'') <> '' and brandName not like '火星%' and brandName not like '原厂%' ) b on a.oeId=b.oeId where a.categoryName='火花塞' ) b on a.vehicleUUID=b.vehicleUUID group by b.brandName

这段 SQL 语句是查询汽车品牌的火花塞车型中，有 VIN 码的车型数量及占比。其中使用了子查询和连接查询，可能会有性能问题。建议优化如下：

1. 尽量避免在子查询中使用聚合函数，可以将子查询的结果存储到临时表中，以提高查询效率。

2. 将子查询中的 ifnull(vin,'') <> '' 转换为 vin IS NOT NULL AND vin <> ''，可以利用索引优化查询。

3. 使用 JOIN 操作时，尽量通过 ON 子句指定连接条件，避免使用 WHERE 子句进行过滤，提高查询效率。

优化后的 SQL 语句如下：

SELECT 
    b.brandName,
    COUNT(DISTINCT a.vehicleUUID) AS have_vin_count,
    COUNT(DISTINCT c.vehicleUUID) AS have_vin_sum_count,
    CONCAT(ROUND(COUNT(DISTINCT a.vehicleUUID) / COUNT(DISTINCT c.vehicleUUID) * 100, 2), '%') AS have_vin_percent
FROM 
    epc_carmodel_skucount a
    INNER JOIN (
        SELECT 
            b.brandName,
            b.vehicleUUID 
        FROM 
            epc_material_sence_model a 
            JOIN (
                SELECT * 
                FROM epc_bom_sence 
                WHERE brandName NOT IN ('演示', '测试', '客服内测') 
                    AND IFNULL(brandName, '') <> '' 
                    AND brandName NOT LIKE '火星%' 
                    AND brandName NOT LIKE '原厂%'
            ) b 
            ON a.oeId = b.oeId 
        WHERE a.categoryName = '火花塞'
    ) b 
    ON a.vehicleUUID = b.vehicleUUID 
    AND a.vin IS NOT NULL 
    AND a.vin <> ''
    LEFT JOIN epc_carmodel_skucount c 
    ON c.vin IS NOT NULL 
    AND c.vin <> ''
GROUP BY 
    b.brandName

这样，可以避免子查询中的聚合函数，使用 INNER JOIN 操作指定连接条件，同时使用 LEFT JOIN 操作获取所有有 VIN 码的车型数量，从而提高查询效率。