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

Try an if statement ...

if @value is null 
    insert into t (value) values (default)
else
    insert into t (value) values (@value)

Answer 2

Don't specify the column or value when inserting and the DEFAULT constaint's value will be substituted for the missing value.

I don't know how this would work in a single column table. I mean: it would, but it wouldn't be very useful.

Answer 3

The easiest way to do this is to modify the table declaration to be

CREATE TABLE Demo
(
    MyColumn VARCHAR(10) NOT NULL DEFAULT 'Me'
)

Now, in your stored procedure you can do something like.

CREATE PROCEDURE InsertDemo
    @MyColumn VARCHAR(10) = null
AS
INSERT INTO Demo (MyColumn) VALUES(@MyColumn)

However, this method ONLY works if you can't have a null, otherwise, your stored procedure would have to use a different form of insert to trigger a default.

Answer 4

The best option by far is to create an INSTEAD OF INSERT trigger for your table, removing the default values from your table, and moving them into the trigger.

This will look like the following:

create trigger dbo.OnInsertIntoT
ON TablenameT
INSTEAD OF INSERT
AS
insert into TablenameT
select
   IsNull(column1 ,<default_value>)
  ,IsNull(column2 ,<default_value>)
  ...
from inserted

This makes it work NO MATTER what code tries to insert NULLs into your table, avoids stored procedures, is completely transparent, and you only need to maintain your default values in one place, namely this trigger.