我有以下SQL代码,它在小数据集上工作得很好。我有一个朋友告诉我,我应该考虑使用SELECT DISTINCT c.name作为循环条件,将其放入MySQL中的FOR循环中。SELECT c.name, c.limit, c.price, c._low, c._high, c.dateWHERE c.e_id IN OR c.pn IN
(SELECT虽然它在概念上看起来很简
当我执行命令时,我尝试迁移我的数据库。php app/console doctrine:migrations:migrate xxxxxxxxxxMigration xxxxxxx was executed but didnot result in any SQL statements.有人能给我解释一下这条信息吗?