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

Probably not the most performance friendly way, but you could create a scalar function that pulls from the information schema with the table and column name, and then call that using the isnull logic you tried earlier:

    CREATE FUNCTION GetDefaultValue
    (
        @TableName VARCHAR(200),
        @ColumnName VARCHAR(200)
    )
    RETURNS VARCHAR(200)
    AS
    BEGIN
        -- you'd probably want to have different functions for different data types if
        -- you go this route
    RETURN (SELECT TOP 1 REPLACE(REPLACE(REPLACE(COLUMN_DEFAULT, '(', ''), ')', ''), '''', '') 
            FROM information_schema.columns
            WHERE table_name = @TableName AND column_name = @ColumnName)

    END
    GO

And then call it like this:

INSERT INTO t (value) VALUES ( ISNULL(@value, SELECT dbo.GetDefaultValue('t', 'value') )