Why is my tsql varbinary data getting truncated

Question

If I get my time zone info from the registry into SQL, I get the full TZI data structure:

DECLARE @TzKey nvarchar(512)
Set @TzKey = 'SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones\Pacific Standard Time'
EXEC master.dbo.xp_regread 'HKEY_LOCAL_MACHINE', @TzKey, 'TZI'

it returns the full binary value

'0xE001000000000000C4FFFFFF00000B0000000100020000000000000000000300000002000200000000000000'

But, if I store it in a variable like this:

DECLARE @TzKey nvarchar(512)
DECLARE @TZI binary(85) 
Set @TzKey = 'SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones\Pacific Standard Time'
EXEC master.dbo.xp_regread 'HKEY_LOCAL_MACHINE', @TzKey, 'TZI', @TZI OUTPUT

Then SELECT @TZI AS TzInfo returns '0xE001'

I have tried every permutation of binary/varbinary and lengths (including MAX) that I can think of.

Any ideas?

Answer 1

I'd do it using an INSERT ... EXEC and then read the value back from the table the result is inserted into:

DECLARE @TzKey nvarchar(512)
DECLARE @TZI binary(85) 
Set @TzKey = 'SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones\Pacific Standard Time'
declare @Results table (Value sysname,Data varbinary(300))
insert into @Results
EXEC master.dbo.xp_regread 'HKEY_LOCAL_MACHINE', @TzKey, 'TZI' --, @TZI OUTPUT
select @TZI = Data from @Results

(Insert usual caveats about using/relying upon undocumented procedures)