我遇到了下面的查询,使用Mysql动态地将行转换为列。有没有人知道3个单引号之前做什么&在Product_Name字段之后?
SET @sql = NULL;
SELECT
GROUP_CONCAT(DISTINCT
CONCAT(
'count(case when Product_Name = ''',
Product_Name,
''' then 1 end) AS ',
replace(Product_Name, ' ', '')
)
) INTO @sql
from products;
SET @sql = CONCAT('SELECT pt.partner_name, ', @sql, ' from partners pt
left join sales s
on pt.part_id = s.partner_id
left join products pd
on s.product_id = pd.prod_id
group by pt.partner_name');
PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;
答案 0 :(得分:2)