Can SQL Server Table Variables Have Indexes?

Can SQL Server table variables have indexes?

In SQL Server 2000, you cannot explicitly index table variables as you can with traditional tables. However, indexes can be created implicitly by defining constraints.

Create unique index on table variables in SQL Server 2000

In SQL Server 2000, you can create a unique index on a table variable by declaring a UNIQUE constraint. This can be achieved by specifying the UNIQUE keyword in the constraint declaration. For example, the following statement creates a table variable and creates a unique index on the Name column:

DECLARE @TEMPTABLE TABLE (
     [ID] [int] NOT NULL PRIMARY KEY
    ,[Name] [nvarchar] (255) COLLATE DATABASE_DEFAULT NULL 
    ,UNIQUE NONCLUSTERED ([Name], [ID]) 
)

By implicitly creating a unique index using the UNIQUE constraint, we ensure that no duplicate values ​​are allowed in the Name column, effectively indexing the Name column for faster data retrieval.

Other index types on table variables

It should be noted that SQL Server 2000 does not support creating non-unique indexes on table variables. Additionally, you cannot explicitly create a clustered index on a table variable. However, you can use a surrogate key or unique identifier column to simulate a non-unique clustered index.

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