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最新文章列表
Rails3: two ways to add index to db table
there is two ways to add index to db table
1. references
if we have two tables , article and commens, the association is 1:M , in order to make search data fast , we should add index to the db table, ...
navicat设置级联删除
.
级联删除:删除包含主键值的行的操作,该值由其它表的现有行中的外键列引用。在级联删除中,还删除其外键值引用删除的主键值的所有行。
语法:
Foreign Key
(column[,...n])
references referenced_table_name[(ref_column[,...n])]
[on delete cascade]
[on upd ...