Sybase-SQL case when clause

DECLARE @current_bind VARCHAR(30)
SET @current_bind = 'tempdb_large_01'
DECLARE @set_tempdb VARCHAR(30)
SET @set_tempdb = 'blub'

CASE WHEN @current_bind='tempdb_large_01' THEN SET @set_tempdb = 'tempdb_large_02'
            WHEN @current_bind='tempdb_large_02' THEN SET @set_tempdb = 'tempdb_large_03'
            WHEN @current_bind='tempdb_large_03' THEN SET @set_tempdb = 'tempdb_large_01'
        ELSE SET @set_tempdb = 'blub'
        END

print 'current: %1! - set: %2!', @current_bind, @set_tempdb
GO
DECLARE @current_bind VARCHAR(30)
SET @current_bind = 'tempdb_large_01'
DECLARE @set_tempdb VARCHAR(30)
SET @set_tempdb = 'blub'

IF @current_bind='tempdb_large_01' BEGIN SET @set_tempdb = 'tempdb_large_02' END
IF @current_bind='tempdb_large_02' BEGIN SET @set_tempdb = 'tempdb_large_03' END
IF @current_bind='tempdb_large_03' BEGIN SET @set_tempdb = 'tempdb_large_01' END

print 'current: %1! - set: %2!', @current_bind, @set_tempdb
GO