unique-constraint

Wondering if Entity Framework 5 supports unique constraints on entity properties? If so, how can I specify that a property should be unique? No, it doesn't. There were plans in the past to include a unique constraint feature in EF 5.0: http://blogs.msdn.com/b/efdesign/archive/2011/03/09/unique-constraints-in-the-entity-framework.aspx But you can see that there is an update on top of the post: Update: this feature has been postponed and will not be included in Entity Framework 5. You can vote on the feature to raise possibly the priority it gets implemented with... http://data.uservoice.com

How can I implement my unique constraints on the hibernate POJO's? assuming the database doesn't contain any. I have seen the unique attribute in @Column() annotation but I couldn't get it to work? What if I want to apply this constraint to more than one column? Bascially, you cannot implement unique constraint without database support. @UniqueConstraint and unique attribute of @Column are instructions for schema generation tool to generate the corresponsing constraints, they don't implement constraints itself. You can do some kind of manual checking before inserting new entities, but in this

I have a table 'users' with 'login' column defined as: [login] VARCHAR(50) UNIQUE NOT NULL Now I want to remove this unique constraint/index using SQL script. I found its name UQ_ users _7D78A4E7 in my local database but I suppose it has a different name on another database. What is the best way to drop this unique constraint? Or at least any... Thanks. SKINDER, your code does not use column name. Correct script is: declare @table_name nvarchar(256) declare @col_name nvarchar(256) declare @Command nvarchar(1000) set @table_name = N'users' set @col_name = N'login' select @Command = 'ALTER TABLE

I have rows in an Oracle database table which should be unique for a combination of two fields but the unique constrain is not set up on the table so I need to find all rows which violate the constraint myself using SQL. Unfortunately my meager SQL skills aren't up to the task. My table has three columns which are relevant: entity_id, station_id, and obs_year. For each row the combination of station_id and obs_year should be unique, and I want to find out if there are rows which violate this by flushing them out with an SQL query. I have tried the following SQL (suggested by this previous

I have little application which allows a user to rate a video. The user can rate only once. So I have defined the uniqueness on the model. But he should be able change his rate. So the save() should update on duplicate key class VideoRate(models.Model): """Users can Rate each Video on the criterias defined for the topic""" user = models.ForeignKey(User) video = models.ForeignKey(VideoFile) crit = models.ForeignKey(VideoCrit) rate = models.DecimalField(max_digits=2, decimal_places=1, choices=RATE_CHOICES) class Meta: unique_together = (('user', 'video', 'crit'),) verbose_name = 'Video Rating'

I have a Table like this one: |UserId | ContactID | ContactName --------------------------------------- | 12456 | Ax759 | Joe Smith | 12456 | Ax760 | Mary Smith | 12458 | Ax739 | Carl Lewis | 12460 | Ax759 | Chuck Norris | 12460 | Bx759 | Bruce Lee I need to add a constraint to this table so that no user can have duplicate contact id's. The users are importing data from various external systems so ContactId will not be unique across the board but will be unique on a per user basis. I know how to create Unique and Non-Null contraints based on single columns but how can I create a unique

I'd like to add a constraint which enforces uniqueness on a column only in a portion of a table. ALTER TABLE stop ADD CONSTRAINT myc UNIQUE (col_a) WHERE (col_b is null); The WHERE part above is wishful thinking. Any way of doing this? Or should I go back to the relational drawing board? PostgreSQL doesn't define a partial (ie conditional) UNIQUE constraint - however, you can create a partial unique index . PostgreSQL uses unique indexes to implement unique constraints, so the effect is the same, you just won't see the constaint listed in information_schema . CREATE UNIQUE INDEX stop_myc ON