postgresql 多列的唯一约束
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Unique Constraint Over Multiple Columns
提问by DaveB
I am using SEAM 2/Hibernate along with PostgreSQL 9 database. I have the following table
我正在使用 SEAM 2/Hibernate 和 PostgreSQL 9 数据库。我有下表
Active Band
===========
active_band_id serial
active_band_user text
active_band_date timestamp
active_band_process integer
I would like to add a constraint that ensures each new entry has a unique combination of active_band_user and active_band_date.
我想添加一个约束，以确保每个新条目都具有 active_band_user 和 active_band_date 的唯一组合。
There could potentially be many attempted inserts per second so I need this to be as efficient as possible, is there a SEAM / hibernate annotation I can use in the entity mapping?
每秒可能有很多尝试插入，所以我需要尽可能高效，是否有可以在实体映射中使用的 SEAM/hibernate 注释？
Thanks in advance
提前致谢
回答by Mikko Maunu
There is no Hibernate annotation that checks uniqueness before insert/update. But there is annotation which will generate such a constraint to database if automatic database creation is used:
没有在插入/更新之前检查唯一性的 Hibernate 注释。但是如果使用自动数据库创建，则有注释会为数据库生成这样的约束：
@Table(
name="ACTIVE_BAND",
uniqueConstraints=
@UniqueConstraint(columnNames={"active_band_user", "active_band_date"})
)
