Ms sql where is not null

25 thg 6, How can we deal with detecting NULL values and replacing them with a non-NULL value? Solution. COALESCE is one of the tools you have in SQL. 30 thg 8, MS SQL Server - How to change an existing column from NULL to NOT NULL? · UPDATE table_name SET col_name = 0 WHERE col_name IS NULL; · ALTER TABLE. The SQL Server NOT NULL constraints simply specify that a column must not assume the NULL. Note that the NOT NULL constraints are always written as column.