SQL Script to find instance name

DECLARE @GetInstances TABLE 

( Value nvarchar(100),  

  InstanceNames nvarchar(100),  

  Data nvarchar(100))  

Insert into @GetInstances 

EXECUTE xp_regread   

    @rootkey = 'HKEY_LOCAL_MACHINE',   

    @key = 'SOFTWARE\Microsoft\Microsoft SQL Server',   

    @value_name = 'InstalledInstances'  

Select InstanceNames from @GetInstances