Insert default value when parameter is null

Question

I have a table that has a column with a default value:

create table t (
    value varchar(50) default (\'something\')
)

I\'m using a stored

Answer 1

The pattern I generally use is to create the row without the columns that have default constraints, then update the columns to replace the default values with supplied values (if not null).

Assuming col1 is the primary key and col4 and col5 have a default contraint

-- create initial row with default values
insert table1 (col1, col2, col3)
    values (@col1, @col2, @col3)

-- update default values, if supplied
update table1
    set col4 = isnull(@col4, col4),
        col5 = isnull(@col5, col5)
    where col1 = @col1

If you want the actual values defaulted into the table ...

-- create initial row with default values
insert table1 (col1, col2, col3)
    values (@col1, @col2, @col3)

-- create a container to hold the values actually inserted into the table
declare @inserted table (col4 datetime, col5 varchar(50))

-- update default values, if supplied
update table1
    set col4 = isnull(@col4, col4),
        col5 = isnull(@col5, col5)
    output inserted.col4, inserted.col5 into @inserted (col4, col5)
    where col1 = @col1

-- get the values defaulted into the table (optional)
select @col4 = col4, @col5 = col5 from @inserted

Cheers...