在浏览一些数据库时,我考虑了正确的数据库设计,在这些数据库中,150000条记录中,有些列只设置了5-20个值。它让我想到低利用率的列应该被转移到透视表中,并希望运行一个报告来告诉我要评估哪个。
我试过用foreach,但对我不起作用。有什么建议吗?
foreach('SELECT table_name,
column_name
FROM information_schema.columns
WHERE table_schema = "mydb"',
'SELECT ${2}, utilization
FROM mydb.${1}.${2}
LEFT JOIN
(
SELECT sum(secondary_email)/count(*) AS utilization
FROM (
SELECT
CASE
WHEN secondary_email IS NULL THEN 0
ELSE 1
END AS secondary_email
FROM offices ) AS c )
GROUP BY ${2} ')
1条答案
按热度按时间h6my8fg21#
我希望得到一个更好的答案,尽管来吧。将输出复制并粘贴到此处,然后删除最终的并集