Can SQL Server table variables have indexes?

In SQL Server 2000, indexes for table variables cannot be explicitly created like traditional tables. However, indexes can be created implicitly by defining constraints.

Create a unique index for table variables in SQL Server 2000

In SQL Server 2000, you can create a unique index for table variables by declaring UNIQUE constraints. This can be done 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 using UNIQUE constraints to implicitly create unique indexes, we ensure that duplicate values ​​are not 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. In addition, clustered indexes cannot be explicitly created on table variables. However, a proxy key or a unique identifier column can be used to simulate a non-unique clustered index.