In SQL, is UPDATE always faster than DELETE+INSERT?

Question

Say I have a simple table that has the following fields:

1. ID: int, autoincremental (identity), primary key
2. Name: varchar(50), unique, has unique index<

Answer 1

One command on the same row should always be faster than two on that same row. So the UPDATE only would be better.

EDIT set up the table:

create table YourTable
(YourName  varchar(50)  primary key
,Tag int
)

insert into YourTable values ('first value',1)

run this, which takes 1 second on my system (sql server 2005):

SET NOCOUNT ON
declare @x int
declare @y int
select @x=0,@y=0
UPDATE YourTable set YourName='new name'
while @x<10000
begin
    Set @x=@x+1
    update YourTable set YourName='new name' where YourName='new name'
    SET @y=@y+@@ROWCOUNT
end
print @y

run this, which took 2 seconds on my system:

SET NOCOUNT ON
declare @x int
declare @y int
select @x=0,@y=0
while @x<10000
begin
    Set @x=@x+1
    DELETE YourTable WHERE YourName='new name'
    insert into YourTable values ('new name',1)
    SET @y=@y+@@ROWCOUNT
end
print @y