unique-index

I'm getting an error running the following Transact-SQL command: CREATE UNIQUE NONCLUSTERED INDEX IX_TopicShortName ON DimMeasureTopic(TopicShortName) The error is: Msg 1505, Level 16, State 1, Line 1 The CREATE UNIQUE INDEX statement terminated because a duplicate key was found for the object name 'dbo.DimMeasureTopic' and the index name 'IX_TopicShortName'. The duplicate key value is (). When I run SELECT * FROM sys.indexes WHERE name = 'IX_TopicShortName' or SELECT * FROM sys.indexes WHERE object_id = OBJECT_ID(N'[dbo].[DimMeasureTopic]') the IX_TopicShortName index does not display. So

If so - What must change in this table ? CREATE TABLE contestants ( idContestants int(10) unsigned NOT NULL AUTO_INCREMENT, idEvent int(10) unsigned NOT NULL, ContestantName varchar(50) DEFAULT NULL, PRIMARY KEY (idContestants), UNIQUE KEY Index_UniqueName (idEvent,ContestantName), ) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=latin1; If you mean case sensitive then: ALTER TABLE `contestants` CHANGE `ContestantName` `ContestantName` VARCHAR( 50 ) CHARACTER SET latin1 COLLATE latin1_bin NULL DEFAULT NULL If you mean case insensitive then: ALTER TABLE `contestants` CHANGE `ContestantName`

I’m interested in learning which technique developers prefer to use to enforce uniqueness in SQL Server: UNIQUE CONSTRAINT or UNIQUE INDEX. Given that there is little difference in the physical implementation of each, how do you decide which is best? Are there reasons other than performance to evaluate the best solution? Are there database management advantages to one or the other? This MSDN article comparing the two is for SQL Server 2000: http://msdn.microsoft.com/en-us/library/aa224827(SQL.80).aspx For most purposes, there's no difference - the constraint is implemented as an index under

What is the diffrence between a unique index and a unique key? Dustin Laine The unique piece is not where the difference lies. The index and key are not the same thing, and are not comparable. A key is a data column, or several columns, that are forced to be unique with a constraint, either primary key or explicitly defined unique constraint. Whereas an index is a structure for storing data location for faster retrieval. From the docs: Unique Index Creates a unique index on a table or view. A unique index is one in which no two rows are permitted to have the same index key value. A clustered

I created a unique index (case description should be unique if IsDelete != 1) CREATE UNIQUE NONCLUSTERED INDEX [UniqueCaseDescription] ON [tblCases] ([fldCaseDescription] ASC) WHERE [IsDeleted] = CAST(0 AS varbinary(1)) WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, SORT_IN_TEMPDB = OFF, IGNORE_DUP_KEY = OFF, DROP_EXISTING = OFF, ONLINE = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY] Then when I run the following procedure it throws 'UPDATE failed because the following SET options have incorrect settings: 'ARITHABORT'. Verify that SET options are correct for use with

I have 3 columns (_id, column1, column2) _id column has been set as autoincrement In database there are some duplicate records, so I want to prevent duplicate records with setting column1 as unique indexer. How do I set a column as unique indexer on sqlite? Or how do I prevent duplicate records? No magic, just SQL: create table yourtablename (_id integer primary key autoincrement, column1 text not null unique, column2 text); _id will not be duplicate in any way because it is primary key, column1 neither because it is unique. 来源： https://stackoverflow.com/questions/8544231/how-to-set-a-column