Question : How to check for null value in trigger?

I have a Table (Tbl_1) into which a record is inserted from time to time. Once a record is inserted into Tbl_1 then I will have to use the columns from the new record and populate other tables. The column values in Tbl_1 can be "NULL". I am planning to write a DB Trigger to take care of creating records in other tables. I am not sure how I can handle existence of "NULL" column values. If a column value is NULL then I will will have to insert "NULL" value.  What is the conditional statement I can make use of to check for "NULL" value? Any help is very much appreciated.

Kind regards

Answer : How to check for null value in trigger?

samble, a trigger is effectively a proc attached to a table, you can easily create a conditional dynamic sql
viz:

CREATE TABLE Customers (CustomerName VARCHAR(100) NULL, CustomerAge INT NULL, ....)
GO
                 
CREATE TRIGGER cust_insert
ON Customers
FOR INSERT AS
DECLARE @sql=varchar(255)
SELECT @sql="insert TableA (col1) select "+CASE WHEN CustomerName = NULL THEN "NULL" ELSE CustomerName  END
SELECT @sql=@sql+"insert TableB (col1) select "+CASE WHEN CustomerAge = NULL THEN "NULL" ELSE CustomerAge  END
..
..
EXEC (@sql)
GO

INSERT Customers SELECT "George W Bush", 99
SELECT * FROM Customers